Spinal cage having deployable member

ABSTRACT

A spinal cage with a wall extending in a longitudinal direction defining an interior space is disclosed. There is also provided a deployable element in movable relation to the spinal cage. In some embodiments, there is a rib, and the rotatable member is engaged at one end with the wall and at the other end with the rib. In some embodiments, the spinal cage is provided with holes for screws that can be directed at adjacent vertebrae for fixation. Such a spinal cage can be used with the spin-plate or with the screws. The screws and the spinal cage may have features that cooperate to prevent back-out of the screws.

CROSS-REFERENCE TO PRIOR APPLICATION

This application claims priority to currently U.S. ProvisionalApplication Ser. No. 61/503,361, filed on Jun. 30, 2011, which isincorporated herein by reference.

This application is also a continuation-in-part of and claims priorityand benefit under 35 U.S.C. §120 to copending U.S. patent applicationSer. No. 12/368,898, filed on Feb. 10, 2009, which is acontinuation-in-part of and claims priority and benefit under 35 U.S.C.§120 to issued U.S. Pat. No. 8,142,508, filed on Jul. 2, 2008, whichclaims priority and benefit under 35 U.S.C. §119(e) to the followingU.S. Provisional App. Nos. 61/037,551, filed on Mar. 18, 2008;61/027,260, filed on Feb. 8, 2008; and 60/947,557, filed on Jul. 2,2007.

This application is also a continuation-in-part of and claims priorityand benefit under 35 U.S.C. §120 copending U.S. patent application Ser.No. 12/368,890, filed on Feb. 10, 2009, which is a continuation of andclaims priority and benefit under 35 U.S.C. §120 to issued U.S. Pat. No.8,142,508, filed on Jul. 2, 2008, which claims priority and benefitunder 35 U.S.C. §119(e) to the following U.S. Provisional App. Nos.61/037,551, filed on Mar. 18, 2008; 61/027,260, filed on Feb. 8, 2008;and 60/947,557, filed on Jul. 2, 2007.

This application is also a continuation-in-part of and claims priorityand benefit under 35 U.S.C. §120 to copending U.S. patent applicationSer. No. 12/752,032, filed on Mar. 31, 2010, which claims priority toU.S. Provisional Application Ser. No. 61/165,267, filed on Mar. 31,2009; which is also a continuation-in-part of and claims priority andbenefit under 35 U.S.C. §120 to abandoned U.S. patent application Ser.Nos. 12/409,435, and 12/409,410, each filed on Mar. 23, 2009 and each ofwhich is a continuation-in-part of and claims priority and benefit under35 U.S.C. §120 to issued U.S. Pat. No. 8,142,508, filed on Jul. 2, 2008,which claims priority and benefit under 35 U.S.C. §119(e) to thefollowing U.S. Provisional App. Nos. 61/037,551, filed on Mar. 18, 2008;61/027,260, filed on Feb. 8, 2008; and 60/947,557, filed on Jul. 2,2007; which is also a continuation-in-part of and claims priority andbenefit under 35 U.S.C. §120 to copending U.S. patent application Ser.No. 12/368,898, filed on Feb. 10, 2009, which is a continuation-in-partof and claims priority and benefit under 35 U.S.C. §120 to issued U.S.Pat. No. 8,142,508, filed on Jul. 2, 2008, which claims priority andbenefit under 35 U.S.C. §119(e) to the following U.S. Provisional App.Nos. 61/037,551, filed on Mar. 18, 2008; 61/027,260, filed on Feb. 8,2008; and 60/947,557, filed on Jul. 2, 2007; which is also acontinuation-in-part of and claims priority and benefit under 35 U.S.C.§120 to the U.S. patent application Ser. No.: 12/368,895 (abandoned);Ser. No. 12/368,893 (abandoned); copending application Ser. No.12/368,890; and issued U.S. Pat. No. 8,100,972, each filed on Feb. 10,2009 and each of which is a continuation of and claims priority andbenefit under 35 U.S.C. §120 to issued U.S. Pat. No. 8,142,508, filed onJul. 2, 2008, which claims priority and benefit under 35 U.S.C. §119(e)to the following U.S. Provisional App. Nos. 61/037,551, filed on Mar.18, 2008; 61/027,260, filed on Feb. 8, 2008; and 60/947,557, filed onJul. 2, 2007; which is also a continuation-in-part of and claimspriority and benefit under 35 U.S.C. §120 to issued U.S. Pat. No.8,142,508, filed on Jul. 2, 2008, which claims priority and benefitunder 35 U.S.C. §119(e) to the following U.S. Provisional App. Nos.61/037,551, filed on Mar. 18, 2008; 61/027,260, filed on Feb. 8, 2008;and 60/947,557, filed on Jul. 2, 2007.

The entire contents of the aforementioned applications are hereinincorporated by reference.

TECHNICAL FIELD

This invention pertains to surgery, such as spinal surgery.

BACKGROUND

Spinal cages are used for spinal fusion (arthrodesis). Sometimes, spinalcages have been used in conjunction with a separate plate that isattached to at least one of the vertebrae involved in the fusion and hasphysically prevented possible motion of the spinal cage away from itsintended position.

SUMMARY

A first exemplary embodiment of the present invention is provided with aspinal cage having a wall extending in a longitudinal direction. Thewall progresses circumferentially in a closed curve within an envelopeof a vertebral cross-section. The closed curve defines an interiorspace.

Another exemplary embodiment of the present invention is provided with aspinal cage having a structure to space vertebrae apart from each other.The embodiment is also provided with a recess facing an interior of thespinal cage and a shaft recess within the recess.

Yet another exemplary embodiment of the present invention is providedwith a spinal cage with a bendable member and a rigid structure.

Another exemplary embodiment of the present invention is provides a spinplate having a blade and a shaft. The blade and shaft being sized to fitwithin a spinal cage. The spin plate may be rotatable with respect tothe cage.

Still another exemplary embodiment of the present invention provides aspinal cage assembly having a spinal cage and a spin plate. A wall ofthe spinal cage extends in a longitudinal direction. The wall progressescircumferentially in a closed curve within an envelope of a vertebralcross-section. The closed curve defines an interior space. The spinplate is engageable with the spinal cage.

Still another exemplary embodiment of the present invention provides aspinal cage assembly having a spinal cage and a deployable member. Awall of the spinal cage extends in a longitudinal direction. The wallprogresses circumferentially in a closed curve within an envelope of avertebral cross-section. The closed curve defines an interior space. Thedeployable member is engageable with the spinal cage.

Another embodiment of the present invention provides an assembly havinga first spinal cage, a second spinal cage, and a spacer between thecages. At least one of the cages is provided with a spin-plate.

Yet another embodiment provides a kit with a spinal cage and a spinplate. The spin plate being suitable to engage with the spinal cage. Thekit may also be provided with a filler piece.

Yet another embodiment of the present invention provides a spinal cageand filler piece assembly. The assembly is provided with a spinal cagewith an internal space, and a filler piece with a geometry to be placedin the internal space.

Another embodiment of the present invention provides a spinal cage withat least three instrumentation interfaces on an external surface. Eachof the instrumentation interfaces being configured for use with adifferent surgical approach.

Another embodiment of the present invention provides a spinal cage withat least two instrumentation interfaces on an external surface. Each ofthe instrumentation interfaces being configured for use with a differentsurgical approach.

Another embodiment of the present invention provides an installation sethaving a spinal implant with a rotatable member, a first installationtool and a second installation tool. The first installation tool isengageable with the spinal implant and the second installation tool iscapable of turning the rotatable member.

Another embodiment of the present invention provides a surgicalprocedure with a first step of creating a first surgical approach. Asecond step of implanting a spinal implant with a deployable memberthrough the first approach. A third step of creating a second surgicalapproach. And a fourth step of deploying the deployable member.

Another embodiment of the present invention provides a trial piece forspinal surgery having a rigid body and a deployable member.

Another embodiment of the present invention provides another surgicalprocedure that is provided with a trial piece having a deployable memberand a spinal cage with a deployable member. The procedure is providedwith the steps of: implanting the trial piece and deploying itsdeployable member; retracting the deployable member and removing thetrial piece; implanting the spinal cage and deploying its deployablemember.

Another embodiment of the present invention provides a spinal cageassembly with a spinal cage, a spin-plate, and a gear associated withthe spin-plate.

Another embodiment of the present invention provides an installationtool for a spinal cage with a deployable member. The tool is providedwith a first member for interfacing with the spinal cage and a secondmember for interfacing with the deployable member.

Another embodiment of the present invention provides a spinal cageassembly and installation tool set. The spinal cage assembly is providedwith a spinal cage, a spin-plate rotatable with respect to the spinalcage. The installation tool is capable of engaging the spinal cage andfurther capable of engaging the spin-plate and rotating the spin platerelative to the spinal cage.

Another embodiment of the present invention provides a spinal cage thathas features to receive the ends of a spin-plate and also has one ormore screw holes capable of accepting a bone screw. In such anembodiment, when the spin-plate is installed in the spinal cage and isin a stowed position, at least a portion of the screw hole(s) is blockedby the blade of the spin-plate, and when the spin-plate is deployed, thescrew hole(s) is/are unblocked or less blocked. Such a spinal cage canbe implanted with neither a spin-plate nor a bone screw, or with aspin-plate, or with one or more bone screws, or with both a spin-plateand one or more bone screws. An embodiment includes a kit containing atleast one spinal cage, at least one spin-plate, and bone screws, whichcan be used together in various combinations. An embodiment includes themethod of implanting into a patient a spinal cage, comprising aspin-plate in a stowed position; rotating the spin-plate to a deployedposition; and inserting at least one screw extending through the spinalcage and into an adjacent vertebra.

Another embodiment of the present invention provides a spinal cage thathas a wall forming a closed path and has a rib connecting two points orlocations on opposed places on the wall, and has a spin-plate having ashaft such that one end of the shaft can be received in the wall and theother end of the shaft can be received in the rib.

Another embodiment of the present invention provides a cutaway featurein either the rib or the wall such that the cutaway feature comprises acentral cutaway region and a connection cutaway region, and theconnection cutaway region connects the central cutaway region with anexternal surface of the rib or wall, and the connection cutaway regionhas a longitudinal direction from the central cutaway region to anexterior of the rib and has a transverse direction orthogonal to thelongitudinal direction, and the central cutaway region has a minimumwidth in the transverse direction and the central cutaway region has amaximum width in the transverse direction, wherein the minimum width ofthe connection cutaway region is smaller than the maximum width of thecentral cutaway region.

Yet another embodiment of the invention provides a spinal cage,containing a rib that defines two cavities within the spinal cage, andhaving two holes one through the wall and one through the rib, thatallow injection of material into the two cavities sequentially after thespinal cage has been implanted into a patient.

BRIEF DESCRIPTION OF THE ILLUSTRATIONS

Embodiments of the invention are illustrated in the followingillustrations.

FIG. 1 is a three-dimensional view, showing an assembly of the inventionin place between vertebrae of a patient's spine.

FIG. 2 is a three-dimensional illustration of a spinal cage.

FIG. 3 is a side view of a spinal cage illustrating lordosis angle.

FIG. 4 a is a top view of the spinal cage. FIG. 4 b is a cross-sectionof the spinal cage, in a plane perpendicular to the longitudinaldirection of the spinal cage.

FIG. 5 is a three-dimensional view of the spinal cage describing groovedetails.

FIG. 6 a is a three-dimensional illustration of a spinal cageillustrating features for interfacing with an installation tool. FIG. 6b is a cross-section of FIG. 6 a.

FIG. 7 a is a three-dimensional illustration of the spinal cage forpurposes of orienting FIG. 7 b and FIG. 7 c. FIG. 7 b is athree-dimensional illustration that is a close-up of a feature on oneinternal surface of the spinal cage, for interacting with thespin-plate. FIG. 7 c is a three-dimensional illustration that is aclose-up of a feature on another internal surface of the spinal cage,for interacting with the spin-plate.

FIG. 8 a is a three-dimensional illustration of a post for the spinalcage. FIG. 8 b is a side view of the same post.

FIG. 9 a is a three-dimensional illustration of the spin-plate. FIG. 9 bis a three-dimensional illustration of the spin-plate from anotherperspective. FIG. 9 c is an end view of the spin-plate.

FIG. 10 a and FIG. 10 b illustrate details of the shape of the disc.

FIG. 11 is a three-dimensional view of a spin-plate having optionalfenestration openings.

FIG. 12 is a three-dimensional view of the spin-plate in a position inthat it is about to be installed into the spinal cage.

FIG. 13 a is a three-dimensional view of the assembled spinal cage andspin-plate, with the spin-plate in the neutral position. FIG. 13 b is athree-dimensional view of the assembled spinal cage and spin-plate, withthe spin-plate in the engaged position.

FIG. 14 a is a front view of the assembled spinal cage and spin-plate,with the spin-plate in the engaged position. FIG. 14 b is a rear view ofthe assembled spinal cage and spin-plate, with the spin-plate in theengaged position.

FIG. 15 a is a side view of the assembled spinal cage and spin-plate,with the spin-plate in the engaged position. FIG. 15 b is a top view ofthe assembled spinal cage and spin-plate, with the spin-plate in theengaged position.

FIG. 16 a is a view, looking along the shaft direction of thespin-plate, of the disc interacting with the posts in the neutralposition. FIG. 16 b is a view, looking along the shaft direction of thespin-plate, of the disc interacting with the posts in the engagedposition.

FIG. 17 a is a localized three-dimensional view of the disc interactingwith the posts in the neutral position. FIG. 17 b is a localizedthree-dimensional view of the disc interacting with the posts in theengaged position.

FIG. 18 is a three-dimensional view showing the disc interacting withthe posts, in the neutral position. In this Figure, the spinal cage hasbeen removed for clarity.

FIGS. 19 a-19 d show interactions between the disc and the posts for aslightly different contour of the disc.

FIG. 20 shows an installation tool connected with a spinal cageassembly.

FIG. 21 is a three-dimensional view showing the tip of the installationtool ready to interact with the spinal cage assembly, in this case atthe anterior face of the spinal cage assembly.

FIG. 22 a is a three-dimensional view showing an installation toolalmost connected to the spinal cage assembly for an anterior insertion.FIG. 22 b is a three-dimensional view showing an installation toolconnected to the spinal cage assembly for a lateral insertion. FIG. 22 cis a three-dimensional view showing an installation tool almostconnected to the spinal cage assembly for an anterolateral insertion atan orientation 45 degrees removed from anterior. FIG. 22 d is athree-dimensional view showing an installation tool almost connected tothe spinal cage assembly for an anterolateral insertion at anorientation 55 degrees removed from anterior.

FIG. 23 is a three-dimensional view of a locker tool that can beinserted centrally in the installation tool for purposes of rotating thespin-plate.

FIG. 24 is a three-dimensional view of the locker tool about to beinserted centrally in the installation tool for purposes of rotating thespin-plate.

FIG. 25 a is a three-dimensional view of the installation tool with thelocker tool inserted in it, all connected to a spinal cage assembly,with the blade in the neutral position. FIG. 25 b is a three-dimensionalview of the installation tool with the locker tool inserted in it, allconnected to a spinal cage assembly, with the blade in the engagedposition.

FIG. 26 is various three-dimensional views of a filler piece that mightbe placed in the empty space inside the spinal cage, when the spin-plateis present.

FIG. 27 illustrates a surgical procedure using one approach forintroduction of the spinal cage assembly and another approach to causerotation of a member of the spinal cage assembly.

FIGS. 28 and 29 illustrate spinal cage assemblies that contain gears tore-orient rotational motion delivered to the spinal cage assembly by atool.

FIG. 30 is a perspective view of an embodiment of the invention, showingthe spinal cage in isolation.

FIG. 31A is a perspective view of an embodiment of the invention,showing the spinal cage and the spin-plate in its undeployed position,without the presence of bone screws.

FIG. 31B is a perspective view of an embodiment of the invention,showing the spinal cage and the spin-plate in its deployed position, andfurther showing two bone screws.

FIG. 32A is a front view of the device of FIG. 31B, with the spin-plateomitted for clarity.

FIG. 32B is a top view of the device of FIG. 31B, with the spin-plateomitted for clarity.

FIG. 32C is a side view of the device of FIG. 31B, with the spin-plateomitted for clarity.

FIG. 33A is a sectional view of the device of FIG. 31B, with thesectional plane coinciding with one of the main planes of a bone screw.

FIG. 33B is a close-up of FIG. 32A.

FIG. 34A is a sectional view (as defined in FIG. 31B) similar to FIG.32A, but with the bone screw omitted.

FIG. 34B is a sectional view (as defined in FIG. 31B) similar to FIG.33A, but with both the bone screw and the snap-ring omitted.

FIG. 35A is a sectional view of the snap-ring alone.

FIG. 35B is a perspective view of a bone screw together with itssnap-ring.

FIG. 36 is a three-dimensional perspective view of a spinal cage thatincludes a rib, and can receive a spin-plate with one end at the walland the other end at the rib.

FIG. 37 is a three-dimensional perspective view similar to that of FIG.36, but from a different vantage point.

FIG. 38A is a three-dimensional perspective view similar to that of FIG.37, but also showing a spin-plate about to be inserted, with thespin-plate in a rotational position suitable to be inserted, whichcorresponds to a stowed (undeployed) rotational position of thespin-plate.

FIG. 38B shows the same spinal cage and spin-plate of FIG. 38A,assembled.

FIG. 39 is a three-dimensional perspective view of the spinal cage andspin-plate assembled together, with the spin-plate showed in a deployedposition.

FIG. 40 is a three-dimensional perspective view similar to FIG. 39, butshowing only the spin-plate and the frustoconical post, with thespin-plate showed in a deployed position.

FIG. 41A is a three-dimensional perspective view of a spinal cage andspin-plate similar to that of FIG. 39, but the details of the spin-plateare such that the stowed position of the spin-plate has the blade in anon-horizontal position.

FIG. 41B shows the spin-plate of FIG. 41A, viewed from a vantage pointopposed to the vantage point of FIG. 41A.

FIG. 41C is a three-dimensional perspective view of the spinal cage andspin-plate of FIG. 39, but with the spin-plate deployed.

FIG. 42A is a sectional view of the spinal cage and spin-plate with theblade undeployed, as shown in FIG. 38B.

FIG. 42B is a sectional view of the spinal cage and spin-plate with theblade deployed, as shown in FIG. 39.

FIG. 43 is a three-dimensional view of an alternate version of spinalcage similar to that of FIG. 38A, but wherein the rib has a grooverather than a slot.

FIG. 44 is a close-up three-dimensional view of an end of thespin-plate.

FIG. 45 is a close-up three-dimensional view of the spin-plate receivedin the spinal cage.

FIG. 46 is a three-dimensional perspective view of yet anotherembodiment of the invention, showing a spinal cage that contains a riband holes that allow for the introduction of material.

DETAILED DESCRIPTION

An embodiment of the invention includes a spinal cage and a deployablemember that can removably fit inside the spinal cage. The deployablemember may be a spin-plate that is able to rotate in order to bedeployed. The spinal cage may be implanted in a patient either with orwithout the deployable member.

FIG. 1 illustrates a spinal cage assembly 10 placed between adjacentvertebrae 70 and 72. Spinal cage 100 is illustrated in FIGS. 2-8. Spinalcage 100 may have a longitudinal direction that extends generally fromvertebra to vertebra 70, 72 in the installed situation. Spinal cage 100may have a longitudinal dimension and related geometry that imposes thedesired relative positioning between vertebrae 70 and 72 when the spinalcage 100 is in place in the patient. This positioning may include alordosis angle, which is an angle indicating the extent ofnon-parallelism between planes enveloping the two ends of the spinalcage.

Referring now to FIG. 2, spinal cage 100 may comprise a wall 110extending in the longitudinal direction of the spinal cage 100 betweenvertebrae 70 and 72. In a plane approximately perpendicular to thelongitudinal direction of the spinal cage 100, wall 110 may progresscircumferentially in a closed curve that may at least approximately fitwithin an envelope of a vertebral cross-section. The closed curve of thewall 110 may define an interior space 112 inside wall 110. In theabsence of a spin-plate as described elsewhere herein, the interiorspace 112 of spinal cage 100 may be substantially open space, availablefor the placement of materials conducive to bone ingrowth or foreventual bone ingrowth.

In some embodiments of the present invention, at least some features ofthe spinal cage 100 may be generally prismatic having a prismatic axis,which is the longitudinal axis of the spinal cage 100, and having across-section perpendicular to the prismatic axis. Along the prismaticaxis, features of spinal cage 100 may generally be constant or repeated.The spinal cage 100 may have a height along the prismatic direction, butit is not necessary for either the external height of spinal cage 100 orthe internal height of spinal cage 100 in the prismatic direction to beuniform everywhere. The spinal cage 100 may be wedge-shaped such thatthe two end faces 114 of spinal cage 100 are not parallel to each other,as described in connection with lordosis and as illustrated in FIG. 3.It is also possible that in localized places, some portions of spinalcage 100 may be missing or features may be cut into what would otherwisebe a strictly prismatic shape. For example, it is possible for the endfaces 114 of spinal cage 100 to have teeth or grooves or other localfeatures that are not strictly prismatic. Referring to FIG. 4, arepresentative cross-section of spinal cage 100, taken perpendicular tothe prismatic axis, is illustrated. This may be considered to be across-section of spinal cage 100 that does not encounter any specialisolated features described elsewhere herein, such as openings, endplatefeatures, or instrumentation interface features.

For spinal cage 100, a wall thickness of wall 110 may be defined as onetraces a path around the internal perimeter. At each point on theinternal perimeter, the wall thickness is defined by a distance to anearest corresponding point on the outer perimeter of the spinal cage100. The wall thickness as a function of position on the internalperimeter may be such that nowhere along the perimeter is there aconstant wall thickness, but rather the wall thickness variescontinuously as a function of position along the perimeter of the spinalcage 100.

The described cross-section of spinal cage 100 may have an externalperimeter. The external perimeter may comprise four main curved segments117 a, 117 b, 117 c, 117 d, and additionally may comprise corner radii118 where the various main curved segments join other main curvedsegments, thereby comprising a total of eight curved segments connectedin succession. Corner radii 118 can be identical to each other ordifferent. Alternatively, the external perimeter of wall 110 mayapproximate an outline that somewhat resembles the shape of anintervertebral disc, such as, for example, the closed curve of the wall110 may approximate a kidney-bean shape. Still other shapes of externalperimeter are also possible.

The described cross-section of spinal cage 100 may have an internalperimeter. The interior perimeter may comprise at least twosubstantially straight-line segments, which may be opposed to each otherand may be parallel to each other. The interior perimeter may comprisefour substantially straight-line segments 119 a, 119 b, 119 c, 119 d atleast some of which may be separated from other similar segments byrounded corner segments 119 e. This is also illustrated in FIG. 4. Ofthese four substantially straight-line segments, two opposedsubstantially straight-line segments may have lengths substantiallyequal to each other. These two segments may be parallel with each other.The other two opposed segments may have lengths different from eachother. These two opposed segments may be parallel with each other. InFIG. 4, the longer of these lengths is labeled L1 and the shorter ofthese lengths is labeled L2.

Between respective straight-line segments 119 a, 119 b, 119 c, 119 d,there may be internal curved corners having a radii of curvature thatare either the same as each other or different from each other. Thesharper internal radius of curvature may occur adjacent to the longer ofthe two substantially straight-line segments in an opposed pair. Thismay be of use for providing space for a spin-plate, as describedelsewhere herein, having a blade that is as long as possible. A largercorner radius may be provided at other corners. This combination offeatures may provide maximum blade space near one extreme of the spinalcage 100 while providing improved local strength near an oppositeextreme of spinal cage 100. It is appreciated that the internalperimeter may have substantially sharp corners or fewer than fourstraight-line segments.

The end faces 114 of spinal cage 100 may be roughened or have featuresappropriate to bite into the bone of adjacent vertebrae 70, 72. Groovesmay be oriented so that it is relatively easy to insert the spinal cage100 into an intervertebral disc space in the desired direction ofinsertion, and relatively more difficult to move the spinal cage 100 inthe opposite direction. For example, the walls of the grooves may slopebackwardly with respect to the intended direction of advancement.Although the illustration shows grooves that extend substantiallylaterally across a full width of the end surface of the spinal cage 100,this is not necessary. It is also possible to have teeth or still othergeometries at end surfaces of spinal cage 100.

The wall 110 may comprise a flat plane on its interior surface thatfaces interior space 112. The flat plane may be substantially alaterally oriented plane, perpendicular to the anterior-posteriordirection of the spinal cage 100. This is illustrated in FIG. 5. If theplane of that interior surface is projected laterally so as to intersectthe entire spinal cage 100, that plane will divide the spinal cage 100into a region that is posterior of the plane and a region that isanterior of the plane. It is possible that the region of wall 110 thatis posterior of that plane may have, on its top and bottom surfaces, atapered surface that is uninterrupted by grooves or teeth. The groovesor teeth may exist anteriorly of that plane.

Referring now to FIG. 7, spinal cage 100 may comprise an opening 120through the wall 110, with the opening 120 having an opening axis.Opening 120 may be a through-hole through the wall 110. Opening 120 maybe located on a plane of symmetry of spinal cage 100, or at theintersection of two planes of symmetry. Opening 120 may be internallythreaded for a portion of its length. Opening 120 may be of a diametersuitable to provide access for a rotational tool for rotating thespin-plate 200 as described elsewhere herein, or for any other desiredpurpose.

Spinal cage 100 may further comprise an opposed concave feature 130located in a part of wall 110 that is opposed to the location of opening120. Opening 120 and opposed concave feature 130 may be coaxial. Opposedconcave feature 130 may have a center of symmetry (such as a line axisof symmetry or a point of symmetry) that is a center of symmetry for atleast some features of opposed concave feature 130, and that center ofsymmetry may lie along the opening axis of opening 120.

Opposed concave feature 130 may comprise any one or more of a recess, ora shaft-receiving blind opening or a shaft-receiving through hole, inany combination. Opposed concave feature 130, or at least a portionthereof may be symmetric about the center of symmetry.

Alternative possibilities include the possibility that both opening 120and opposed concave feature 130 could be through-holes, and that one orboth of opening 120 and opposed concave feature 130 could be steppedopenings or otherwise have a configuration more complicated than asimple cylindrical opening. As described elsewhere herein, it ispossible that either or both of opening 120 and opposed concave feature130, or a recess associated with either or both of 120, 130 might have aperiphery that is not completely circular or is non-axisymmetric.Opening 120 and opposed concave feature 130 taken together may besuitable to define a position or an axis of a shaft of a spin-plate asdescribed elsewhere herein.

A possible orientation is that opening 120 may be at the anterior of thespinal cage 100 and opposed concave feature 130 may be at the posteriorof the spinal cage 100. Opening 120 may be adapted for use ininterfacing with an installation tool, as described elsewhere herein.

The spinal cage 100 may have a groove 150 or two grooves 150, 160 thatextend at least approximately in the longitudinal direction of thespinal cage 100. The groove or grooves 150, 160 may be on aninterior-facing surface of the wall 110 of spinal cage 100. If there aretwo grooves 150, 160, the grooves 150, 160 may be located so that theysubstantially face each other. The groove(s) 150, 160 may extend fromfeatures 120, 130 all the way to one end of the spinal cage 100. Ifthere are two grooves 150, 160, the grooves 150, 160 may besubstantially parallel to each other and may extend in the samedirection as each other. The grooves 150, 160 are shown as beingstraight although they do not have to be straight. In one embodiment,the grooves 150, 160 may be located such that their respective axes liein a plane that is a plane of symmetry of the spinal cage 100.

It is possible that a groove 150, 160 may comprise an entrance regionsuch as a tapered or curved entrance region 156 that may help the end ofa component entering groove 150, 160 to find its appropriate place whileaccommodating inexact initial placement of the component with respect togroove 150, 160.

The two grooves 150, 160 may be identical to each other or they could bedifferent from each other. For example, grooves 150, 160 may haverespective groove widths that are different from each other. This mayhelp to create a situation in which there is only one possible way for aspin-plate to be installed into the spinal cage 100. Such a situationmay be desirable for preventing possible mistakes of assembly orprocedure. Having grooves 150, 160 be different from each other may beappropriate to accommodate differences between the two ends of thespin-plate in terms of function or dimensions of the respective shaftends, as discussed elsewhere herein.

Referring now to FIG. 6, the spinal cage 100 may comprise aninstallation tool interface for an insertion tool to connect to thespinal cage 100 during installation. The installation tool interface maydefine an insertion direction that may be at least approximatelyperpendicular to the local surface of the spinal cage 100 at the placewhere the insertion tool connects to the insertion tool interface. Theinsertion direction may be at least approximately parallel to the axisof the opening 120, which in turn may correspond to the axis of rotationof the spin-plate (described elsewhere herein) when the spin-plate isinstalled in the spinal cage 100.

This design could be used if the surgical approach for placement of thespinal cage 100 is an anterior surgical approach. For such a situation,the axis of the opening 120 could lie in a plane of symmetry of thespinal cage 100.

It is also possible that the spinal cage 100 could be designed for usewith surgical approaches other than a straight anterior approach. Forexample, the spinal cage 100 could be designed for use with a lateralsurgical approach. Still other surgical approaches may be possible, withcorresponding choices of locations of opening 172.

FIGS. 6 a, 6 b illustrate a spinal cage 100 that comprises interfacefeatures compatible with four different surgical approaches.

It is possible that the spinal cage 100 may comprise a plurality ofinterface features 172, such as openings on an external surface of thespinal cage 100, with an interface feature 172 corresponding to eachpossible surgical approach. For example, there may be an interfacefeature, such as an opening 172 a in the anterior surface of the spinalcage 100, for use with an anterior approach. There further may be aninterface feature, such as an opening 172 b in the lateral surface ofspinal cage 100, for use with a lateral approach. Interface feature 172b may be located approximately 90 degrees away from opening 172 a, asviewed in FIG. 6. Still further, for use with an anterolateral approach,there may be an opening 172 c through the external surface of the spinalcage 100 oriented at approximately 45 degrees away from the anteriordirection. It is still further possible that an instrumentationinterface may be provided for insertion of the spinal cage 100 from adirection that is closer to anterior than it is to any other direction,but is still somewhat removed from anterior. For example, the directionmay be oriented approximately 15 degrees removed from anterior. In sucha structure, there may be provided an opening 172 d whose axis isoriented approximately 15 degrees removed from anterior. In the samestructure, the opening 172 d may be translationally offset from a true15 degree opening pointing at the center of the spinal cage 100, so asto avoid overlap with other features of spinal cage 100 with whichoverlap might occur without such offset. It is further possible that the45 degree interface opening 172 c and the 15 degree interface opening172 d may be provided on opposite sides of the anterior interfaceopening 172 a, again to avoid overlap of such openings with each other.

In general, interface openings 172 may be internally threaded. It isfurther possible that an interface opening, such as 172 a, may haveinterface features such as an internal thread. These threads may occupyonly a portion of the depth of opening 120 that may be coaxial with 172a. Such threads may be on a more exterior portion of opening 172 a. Atthe same time, opening 172 a may comprise features that interface with aspin-plate as described elsewhere herein. Such features may be on a moreinterior portion of opening 172 a. The portion of opening 172 a thatinterfaces with the spin-plate may be free from threads. The threads onsome of the interface openings 172 may be identical to the threads onsome other interface openings 172. Alternatively, threads on someinterface openings may be different from the threads on other interfaceopenings. For example, threads on opening 172 a, which is illustrated asbeing a multi-purpose opening, may be larger than threads on openings172 b, 172 c, 172 d, which are illustrated as serving only asinstrumentation openings.

It is further possible that a groove 174 may be provided on the externalsurface of the spinal cage 100, extending so as to meet at least some or(as illustrated) all of these interface openings 172. The groove 174 maybe located at least approximately on a plane of symmetry of spinal cage100, such as the midplane of the spinal cage 100, such plane beingperpendicular to the prismatic axis of the spinal cage 100. This groove174 on the exterior surface may extend more than 90 degrees of angleprogressing around the external perimeter of spinal cage 100, such asextending through at least approximately 135 degrees of circumference.The groove 174 may cooperate with a corresponding feature on aninstallation tool. For example, groove 174 may cooperate with a featureof an installation tool to serve an anti-rotation function.

Various different spinal cages 100 of different sizes may be designed sothat at least some of them share the same installation tool interface.such as curvature of the spinal cage external surface near the toolinterface, dimensions of the tool interface groove 174, dimensions ofinterface openings 172 a, 172 b, 172 c, 172 d, etc. In this way, aninstallation tool can interface with multiple size variations of spinalcages 100.

Dimensions of the spinal cage 100 or of various spinal cages in a setmay include an overall height that ranges from 8 to 16 mm, footprintdimensions that range from 27 mm to 39 mm in width and 21 mm to 30 mm indepth, and lordosis angles that range from 8 degrees to 15 degrees. Theset of spinal cage sizes may for example comprise a typical small sizeand a typical large size, with most patients being able to accept one orthe other of those two sizes. There may further be provided an extremelylarge size and an extremely small size for patients needing thoseparticular sizes. For each individual footprint size of a spinal cage, avariety of spinal cages may be provided having respective combinationsof heights and lordosis angles.

Referring now to FIGS. 7 and 8, the spinal cage 100 may comprise one ormore posts 190 that may protrude from the spinal cage wall 110 into theinterior space 112 of the spinal cage 100.

There may be two posts 190 a, 190 b that may be located 180 degreesapart from each other with respect to a rotation center. The rotationcenter may be the center of feature 130 or on the axis of opening 120.

A simple possible form of post 190 is a cylindrical post, part of whichis embedded in wall 110, and part of which protrudes into the interiorspace 112 of spinal cage 100.

Alternatively, the post 190 may comprise a stem 192 and a head 194, withthe head 194 being larger in a transverse direction than is the stem192. The stem 192 and the head 194 may be substantially coaxial,although this is not necessary. It is possible that the entire post 190may be axisymmetric, although this is not necessary.

The post 190 may be cylindrical where it engages the spinal cage 100,and it may be cylindrical with a larger diameter where it does notengage the spinal cage 100. The post 190 may protrude into interiorregion 112 of spinal cage 100 at the portion that does not engage thespinal cage. It is appreciated that shapes other than cylindrical arealso possible for post 190.

The stem 192 may be capable of being embedded into the spinal cage. Forexample, the stem 192 may fit with a press fit or an interference-fitwithin an opening in the spinal cage wall 110. The stem 192 may furthercomprise barbs or similar features that may be oriented in such adirection that inserting the stem 192 into the spinal cage wall 110 isrelatively easier than removing the stem 192 from the spinal cage 100.Alternatively, posts 190 could be molded into spinal cage 100. As stillanother alternative, it is also possible that the post could be integralwith the wall 110 of spinal cage 100.

The head 194 of the post 190 may be frustoconical. If frustoconical, thehead 194 may have a head taper angle as illustrated, with the head beinglarger nearest to the wall 110 and smaller away from wall 110. The taperangle of the frustoconical head 194 may be chosen for purposes ofinteraction with features of the spin-plate, as described elsewhereherein. For example, a possible angle of taper of the frustoconical head194 is approximately 15 degrees total included angle (7.5 degreesconical half-angle). This angle may be chosen appropriately so that whenspin-plate 200 is in place, the frustoconical angle of the head 194, anda corresponding angle near the edge of the disc 290 that interacts withpost 190, combines to trap post 190 in position in wall 110. Thisstructure makes it impossible for post 190 to migrate out of the wallopening in which it is inserted. It is also possible that thecooperating angles, as spin-plate 200 is rotated, may urge spin-plate200 forward possibly making some elastic deformation of spinal cage 100available to help the rotation slip past certain detents in the normalcourse of rotation.

It is possible that the wall 110 of spinal cage 100 can be deflectablewithin an elastic limit such that under certain circumstances, the shapeof the closed curve of wall 110 becomes slightly different from what itis in an undeflected-condition. For example, wall 110 can be deflectablein an anterior-posterior direction such that the distance between theanterior and posterior portions of the wall 110 increases. The amount ofdeflection can be suitable for snapping a spin-plate into place or canbe involved in rotating the spin-plate, both of which are describedelsewhere herein.

As described elsewhere herein, the wall 110 may be generally straightalong the prismatic direction, with the possible exception of localgeometric features. The wall may be straight both interiorly andexteriorly. Alternatively, it is possible that the wall 110 of thespinal cage 100 may have an inner surface (facing interior space 112)that is concave along a longitudinal direction from a first end to asecond end of the spinal cage 100. Such a concave inner surface mayprovide increased space for bone ingrowth or for placement of materialfor aiding the ingrowth of bone, as compared to a wall 110 whose innersurface is substantially straight or prismatic.

The spinal cage 100 may be chosen to have a desired radiopacity. Forexample, the spinal cage 100 may be made entirely or mostly ofradiolucent material such as a polymer (for example,polyetheretherketone (PEEK)). If the spinal cage 100 is made of such aradiolucent material, the spinal cage 100 could additionally compriseradiopaque markers placed in it at desired locations having knowndimensions, spacing or orientation for later use during radiography. Forexample, the radiopaque markers could be or could comprise tantalum. Theradiopaque markers could be in the form of spheres, rods or other simpleshapes. The radiopaque markers could be press-fitted into appropriatecavities in spinal cage 100. Alternatively, radiopaque markers could bemolded into spinal cage 100. The radiopacity of the spinal cage 100 maybe chosen in combination with the radiopacity of the spin-plate 200 toachieve a desired purpose.

Embodiments of the invention can include a spin-plate 200 or moregenerally a deployable member. Spin-plate 200 is illustrated by itselfin FIGS. 9-11. The spin-plate 200 may comprise a shaft 210 and a blade230. Blade 230 may, as illustrated, be a substantially planar elementthat may have some sharpened edges. The plane of blade 230 may besubstantially perpendicular to the axis of shaft 210. The blade 230 andthe shaft 210 may be sized to fit inside spinal cage 100 for certainrotational positions of spin-plate 200, and to extend beyond theenvelope of spin-plate 200 for other rotational positions of spin plate200.

The blade 230 may be integral with shaft 210. Alternatively, blade 230may be made as a separate part from shaft 210 and may be connected toshaft 210 either temporarily or permanently. It is possible that if theshaft 210 and the blade 230 are not made integrally with each other,they might be made separately from each other in such a way that asurgeon would have the ability to select and assemble blade 230 andshaft 210 to each other as desired at around the time of surgery. Theremay be, as illustrated, only one blade 230. Alternatively, it ispossible that the spin-plate 200 could comprise or could be used withmore than one blade 230 simultaneously. If so, the various blades 230either could be identical to each other or could differ from each otherin their dimensions, materials or in any other feature. For example, theposition of blade 230 on spin-plate 210 could be chosen so as to providea desired position of the blade 230 with respect to anatomical featuressuch as regions or types of bone within a vertebra. If the blade 230 isnear the middle of the length of spin-plate 210, blade 230 when deployedis likely to interact with cancellous bone. If blade 230 is closer toand end of spin-plate 210, blade 230 when deployed is more likely tointeract with cortical bone. The position of spin-plate 230 on shaft 210also may affect how much spreading-apart of the vertebrae could beacceptable at the location of blade 230. This may be due to patientmotion prior to bony fusion, which in turn could affect how muchextension of the spin-plate 230 from the envelope of the spinal cage 100may be needed in the deployed condition to assure continued contactbetween the blade 230 and the vertebrae 70, 72.

Blade 230 could have an edge, which is the leading edge for the intendeddirection of rotational advancement of the blade into bone that issharpened but otherwise smooth and continuous, as illustrated in FIG. 9and elsewhere. Alternatively, it is possible that the blade 230 couldcomprise serrations or a plurality of teeth on surfaces that face bonefor an intended possible direction of rotation for advancing the blade230 into the bone. Such serrations or teeth may help provide suitableproperties for cutting into bone. It is possible that the blade 230could comprise at least one opening through the blade 230 or at leastone indentation from an edge of the blade 230. Such openings orindentations could provide shape irregularities that newly formed bonecan grow through or into or around, thereby helping to anchor the blade230 in position in the patient after bone ingrowth has occurred. It ispossible that the blade 230, in cross-section in a plane that includesan axis of rotation of the shaft 210, could comprise an undercutconfiguration. Such a configuration could also contribute to anchoringof the blade 230 and the spin-plate 200 generally into bone.

Various parts of the spin-plate 200 may have respective dimensions indirections that are radial or perpendicular to the axis of rotation ofspin-plate 200. The shaft 210 may have a dimension such as a shaftdiameter that is less than a corresponding maximum radial dimension ofthe blade 230.

Shaft 210 may comprise flats on the shaft on at least one end or bothends of the shaft 210.

An end of shaft 210 could have geometry as illustrated in FIG. 9 andelsewhere, comprising circular arcs and flats. The flats 222 a, 222 band 232 a, 232 b may be parallel with each other. Flats at opposite endsof shaft 210 also may be parallel with each other. It is furtherpossible that the end of shaft 210 could have still other geometriesinstead of the described circular arc and flats. It is possible that theend of the shaft may be non-axisymmetric. An end of shaft 210 maycomprise a cross-section that is non-circular having, at various linespassing through the axis perpendicular to the axis, a smallestcross-dimension of the enlargement 250 and a largest cross-dimension ofthe enlargement 250. The orientation of the smallest cross-sectiondimension may be approximately perpendicular to the orientation of thelargest cross-section dimension. As a result, the spin-plate 200 may beable to pass translationally longitudinally through groove 150, 160 forcertain angular orientations of spin-plate 200 with respect to spinalcage 100, while being unable to pass through groove 150, 160 for otherangular orientations.

The shaft 210 might comprise a rotational tool interface 280 suitable totransmit rotation from a tool to the spin-plate 200. Rotational toolinterface 280 could be provided either at one end or at both ends ofspin-plate 200. For example, if the spin-plate 200 can only be assembledinto spinal cage 100 in one orientation, it may be that a rotationaltool interface 280 for a rotational driving tool is not needed at bothends of shaft 210, but rather is only needed at one end. The shaft 210may be designed accordingly.

The rotational tool interface 280 could be elongated such as a rectangleor rounded-rectangle. The long direction of the elongated tool interfacecould be parallel to the flats on the shaft 210 or flats on anenlargement of the shaft 210 at that end of the shaft 210.

A feature at one end of the shaft 210 may be different from a feature atthe other end of the shaft 210. For example, the difference may be in awidth of a flat at or near an end of the shaft 210, or more generallymay be a smallest cross-section dimension of the enlargement 250. Asdescribed elsewhere herein, such a feature may have a function indetermining whether a spin-plate 200 can be inserted into the spinalcage 100 in only one configuration or whether a spin-plate 200 can beinserted in two configurations by reversing the ends of the spin-plate200. In some circumstances, it may be useful if the spin-plate 200 fitsinto the spinal cage 100 in only one configuration.

Referring now to FIG. 11, in some embodiments of the present invention,it is possible that the spin-plate shaft 210 may for at least for aportion of its length be hollow. For example, the shaft 210 may have ahollow interior 214 that is open at the end having tool interfacefeature 280, and that may be closed at the end opposite the open-endedend. Furthermore, communicating with the hollow interior 214 of theshaft 210, there may be fenestrations 216 that may be at leastapproximately transverse to the rotational axis of shaft 210. Thefenestrations 216 may be at least approximately perpendicular to therotational axis of shaft 210. The fenestrations 216 may be suitable toallow passage of bone-growth-promoting material or other liquid orsemi-solid material. The end of the shaft 210, at which the hollowinterior 214 is accessible, may be the end that is most accessible tothe surgeon. Such as, for example, the end that has an interface 280 toaccept tooling to cause rotation of the spin-plate 200. This end of theshaft 210 may further comprise a feature to interface with an injectiondevice for injecting bone growth promoting material or other materialinto the shaft interior 214.

Fenestrations 216 through the side wall of the shaft 210 may exit theshaft 210 in such an orientation that, when the spin-plate 200 is in itsfinal position in which the blade 230 is deployed to interact withadjacent vertebrae, the fenestrations 216 point laterally in thepatient's body. Similarly, it is possible that the fenestrations 216 maypoint in an oblique direction, partly laterally but also having acomponent in the cephalad-caudal direction. In the illustration,spin-plate 200 is illustrated in its orientation in which the blade 230is deployed to interact with adjacent vertebrae.

The spin-plate 200 may be designed to have a desired radiopacity for aspecific purpose. The radiopacity of spin-plate 200 may be chosen incombination with the radiopacity of the spinal cage 100. Within thespin-plate 200 itself, the shaft 210 and the blade 230 could be made ofthe same material and may even be integral with each other. For examplethe entire spin-plate 200 could be made of metal such as a biocompatibletitanium alloy. Alternatively, it is possible that the shaft 210 and theblade 230 could be made of different materials having differentradiopacities. If less than the entire spin-plate 200 is radiopaque,then the components or features of the spin-plate 200 that areradiopaque could be placed having known dimensions or orientations orseparation distances between the features or components. Dimensions orfeatures of spin-plate 200 could be chosen for radiographic purposes. Itis possible that some part of the spin-plate 200 could be moreradiopaque than another part of the spin-plate 200. For example, theshaft 210 could be more radiopaque than a remaining part of thespin-plate, or the blade 230 could be more radiopaque than a remainingpart of the spin-plate 200. If multiple blades 230 are present,individual blades 230 could have different radiopacities.

It is possible that the blade 230 of spin-plate 200, or any other partof spin-plate 200, may have a coating of a substance that is a member ofthe calcium phosphate family. For example, the coating may comprisehydroxyapatite or tricalcium phosphate. Such substances can be depositedonto a substrate, for example a metal substrate such as the blade 230 ofspin-plate 200, by methods such as plasma spraying. Such coatings maypromote the growth and interaction of bone with the component that theyare deposited upon.

Some deployable parts may be resorbable. For example, the blade 230, orsome portion thereof, may be resorbable. The blade 230 may, for example,comprise a resorbable polymer. If the blade 230 is resorbable, it isstill possible that shaft 210 may be nonresorbable. Similarly, someportion of blade 230 may be nonresorbable.

The resorption time of the resorbable deployable part may be chosen sothat the deployable part stays intact while bone growth is occurring andwhile there may be some risk of expulsion of the spinal cage. But, bythe time resorption has completed, bone growth has occurred sufficientlyto achieve fusion between the desired vertebrae. Use of a resorbabledeployable part need not be limited to the described design involvingspin-plate 200, but could be used as well with other designs of spinalfusion cages having deployable members that may be deployable by anyform of motion.

The spin-plate blade 230 may be located so as to cut into cancellousbone in adjacent vertebrae rather than into cortical bone, because thecancellous bone might be easier to cut into. For example, if thespin-plate blade 230 comprises resorbable materials, the blade 230 mightbe less tough than would be the case for a metal blade, and so the blade230 might be located so as to cut into cancellous bone. Spin-plate blade230, if it is not itself radiopaque, may comprise a radiopaque marker.

Embodiments of the invention may include an assembly comprising thespinal cage 100 and the spin-plate 200. FIGS. 12-15 illustrateassemblies or features thereof. In general, the spin-plate 200 and thespinal cage 100 may be separable from each other. Spinal cage 100 may besuitable to be implanted in a patient either with or without spin-plate200 as dictated by surgical needs.

It has been described elsewhere herein that the spinal cage 100 may havean internal perimeter whose shape is as illustrated in FIG. 4. The useof a sharper radius of curvature and the longer of the two unequalsegments L1 compared to L2 may occur on the face nearest where thespin-plate blade 230 exists in the assembly. This may provide space forthe blade 230 to rotate and may help to allow blade 230 to be as long aspossible within geometric constraints of the overall spinal cage 100 andthe assembly. When the spinal cage 100 is assembled with a correspondingspin-plate 200, the lateral dimension of the longer flat of the internalperimeter, labeled L1 in FIG. 4, may be at least as large as the largestend-to-end dimension of the blade 230 on the spin-plate 200.Alternatively, L3, which is the distance between the two opposedsubstantially straight-line segments, may be at least as large as thelargest end-to-end dimension of the blade 230 on the spin-plate 200.This may be true for all cross-sections of spinal cage 100 or at leastfor a cross-section that passes through the rotational axis ofspin-plate 200.

Various sizes of spinal cages 100 and various sizes of spin-plates 200may be manufactured and may be provided to a surgeon in advance ofsurgery. The respective spinal cages 100 and spin-plates 200 may be suchthat various different spin-plates 200 can be inserted into a particularspinal cage 100, depending on the choice of the surgeon. The variousdifferent spin-plates 200 may differ from each other in some geometricfeature. For example, the spin-plates 200 may differ in the respectivelengths of their respective blades 230, so as to provide differentdepths of penetration of the blade 230 of spin-plate 200 into the boneof the adjacent vertebrae. The dimension L1 or alternatively thedimension L3 may be larger than the end-to-end dimension of thelargest-bladed spin-plate that is contemplated to be used with aparticular spinal cage 100. Of course, it is also possible to surgicallyimplant a spinal cage 100 alone without the presence of any spin-plate200. All of these decisions as to which spin-plate 200 to use with aparticular spinal cage 100, or even whether to use any spin-plate 200 atall, can be made around the time of or during surgery.

The spin-plate 200 and the spinal cage 100 may be such that thespin-plate 200 can be engaged with or disengaged from the spinal cage100 without the use of a tool. The engagement of the spin-plate 200 withthe spinal cage may be able to be performed with a snap fit. It may alsobe possible to disengage the spin-plate 200 from the spinal cage byundoing the snap fit. Alternatively, a tool could be used to assist ininsertion or disengagement. The engagement of the spin-plate 200 withthe spinal cage 100 may be in such a way as to provide a positiveindication that the spin-plate 200 has entered the spinal cage 100 andhas reached the place where rotation of the spin-plate 200 can beperformed. The positive indication can be tactile, such as a sharpchange in the amount of force needed to advance the spin-plate 200 intothe spinal cage 100, or audible, or both.

Engagement of the spin-plate 200 with the spinal cage may involveinteraction at both ends of the spin-plate 200 with the wall 110. Thespin-plate 200 may have a first end engaged with a first place on thewall 110 of the spinal cage and a second end engaged with a second placeon the wall 110 of the spinal cage. The first place and second place maybe substantially opposed to each other. It is possible that the firstand second places may be on anterior and posterior portions of the wall110 of the spinal cage, respectively. Other spin plate locations arealso possible.

In general, it is possible that there is an initial angular position ofthe spin-plate 200 relative to the spinal cage 100, in which the blade230 is contained within the spinal cage 100. That could be theconfiguration in which the assembly is moved into the patient's body.There can also be a final angular position of the spin-plate 200relative to the spinal cage 100, in which the blade 230 extends beyondan envelope of the spinal cage 100. That could be the configuration atthe completion of surgery. Blade 230 may have a maximum end-to-enddimension that is greater than the longitudinal dimension of the spinalcage 100 in at least some places in the spinal cage 100. This may ensureinteraction of the blade 230 with bone when the blade 230 is in adeployed condition. Blade 230 may have a side-to-side dimension that maybe measured in a direction approximately perpendicular to the directionin which the blade end-to-end dimension is measured. The blade 230side-to-side dimension may be less than a longitudinal dimension ofspinal cage 100 in at least some places in the spinal cage 100. This mayensure that when the blade 230 is in an undeployed condition, it doesnot interact with bone.

The spin-plate 200 may be designed so that the deployed angular positionof the blade is 90 degrees removed from the undeployed angular positionof the blade.

To go from the initial configuration to the final configuration, thespin-plate 200 may be capable of rotating 90 degrees away from theinitial angular position in a specified direction of rotation.Embodiments illustrated herein permit 90 degrees of rotation in aspecified direction of rotation, but more than 90 degrees of rotation isdifficult or impossible, and rotation in the unintended direction ofrotation is difficult or impossible. Alternatively, it is possible thatrotation of the spin-plate 200 relative to the spinal cage might beangularly unrestricted, allowing as much as 360 degrees or more ofrotation of the spin-plate 200 relative to the spinal cage 100. Ingeneral, the assembly may be such that when the spin-plate 200 isinstalled in the spinal cage 100, the interior of the spinal cage 100 issubstantially open and unblocked except for the spin-plate 200.

The spin-plate 200 and the spinal cage 100 may be designed such that thespin-plate 200 can fit into the spinal cage 100 in only oneconfiguration (as opposed to being able to fit into spinal cage 100 witheither end of spin-plate 200 in either of the two grooves 150, 160). Ifthe spinal cage comprises two grooves 150, 160 and the spin-plate 200comprises two corresponding flat-to-flat dimensions, the two grooves150, 160 can be of unequal dimensions and the flat-to-flat dimensionscould be correspondingly different. As a result of this, the spin-plate200 and the spinal cage 100 may fit together in only one configuration.The spin-plate 200 and the spinal cage 100 may be designed so that theat one end of the spin-plate 200, the flat-to-flat dimension of theshaft is slightly less than the width of groove 150, and at the otherend of the spin-plate 200, the flat-to-flat dimension of the shaft isslightly less than the width of groove 160. It may be useful formistake-proofing if the spin-plate 200 fits into the spinal cage 100 inonly one configuration. Alternatively, the various components may bedesigned so that the spin-plate 200 can be placed into spinal cage 100in either end-to-end configuration.

In general, an end of spin-plate 200 may have a non-circularcross-sectional shape having a minimum cross-sectional dimension and amaximum cross-sectional dimension. In order to enable sliding-in of aparticular end of spin-plate 200 into a particular groove 150, 160, theminimum cross-sectional dimension of the end of spin-plate 200 may beless than the width of the particular groove. Following successfulsliding-in, in order to allow rotation of an end of spin-plate 200within opening 120 or opposed concave feature 130, the maximumcross-sectional dimension of the end of spin-plate 200 may be less thana transverse dimension of opening 120 or opposed concave feature 130.

Alternatively, it is possible that the two ends of shaft 200 andcorresponding features of spinal cage 100 may be substantially identicalto each other. In this situation, it may be possible to installspin-plate 200 into spinal cage 100 in a first orientation or in asecond orientation in which the ends of spin-plate 200 are interchangedwith each other. However, even in this situation the spin-plate need notbe symmetric from end-to-end. For example, blade 230 might be located onshaft 210 at a location that is not the midpoint of shaft 210, andhaving the ability to insert spin-plate 200 into spinal cage 100 in twoopposite end-to-end orientations would provide two choices for theposition of the blade 230.

The spinal cage 100 and the spin-plate 200 may be such that thespin-plate 200 can be captured within spinal cage 100, at least forcertain relative rotational positions. It is possible that when thespin-plate 200 is in the spinal cage 100, the spin-plate 200 couldexperience axial force from spinal cage 100 such as from elasticdeformation of spinal cage 100. In this situation, it is possible thatthere could be a designed amount of axial force exerted by spinal cage100 upon spin-plate 200, resulting in a designed amount of frictionagainst rotation of spin-plate 200 relative to spinal cage 100 andessentially no permitted axial motion of spin-plate 200 relative tospinal cage 100. Alternatively, it is possible that the spin-plate 200does not experience force exerted on it by spinal cage 100 along therotational axis direction of spin-plate 200. The apparatus may bedesigned to lack such force if it is uncertain or unpredictable what theactual amount of such force would be. In such a structure, it ispossible that there could be a slight amount of permitted axial motion(play) of the spin-plate 200 relative to spinal cage 100 along therotational axis direction of spin-plate 200. Alternatively, thedimensions might be such that nominally there is substantially nopermitted axial motion of spin-plate 200 relative to spinal cage 100 andalso substantially no axial force exerted by spinal cage 100 uponspin-plate 200 along the direction of the axis of rotation of spin-plate200. It is possible either for disc 290 to bear against aninterior-facing surface of wall 110 or for blade 230 to bear against aninterior-facing surface of wall 110, or both. It is possible thatneither disc 290 nor blade 230 bears against an interior-facing surfaceof wall 110.

Geometrically, the spin-plate 200 can have two extreme points at leastapproximately corresponding to extreme ends of spin-plate 200 along therotational axis of spin-plate 200. In the assembled configuration, wherespin-plate 200 is installed in spinal cage 100, there can be arespective nearest-contact point of spinal cage 100 that is eithertouching or nearest to each of the respective extreme points ofspin-plate 200. The distance between the two nearest-contact points canbe greater than or approximately equal to the distance between the twoextreme points of the spin-plate 200. For the case of creating frictiondue to axial loading on the spin-plate 200, the distance between the twonearest-contact points (when the spinal cage is undeformed) could beless than the distance between the two extreme points of the spin-plate200.

The spinal cage 100 and the spin-plate 200 may be such that spinal cage100 is capable of deflecting within an elastic limit, by an elasticdeflection distance. In such a structure, everywhere along an insertionpath of spin-plate 200 into spinal cage 100 there is a minimum cleardimension in a direction roughly corresponding to the axis of rotationof spin-plate 200. That minimum clear dimension plus an elasticdeflection distance, is greater than the maximum overall length ofspin-plate 200.

The spinal cage 100 and the spin-plate 200 may be such that thespin-plate 200 is capable of entering the spinal cage 100 and becomingtrapped within spinal cage 100 while being able to rotate relative tospinal cage 100 after spin-plate 200 has become trapped within spinalcage 100.

Alternatively, the length of the spin-plate 200 could be such that thespin-plate 200 fits into spinal cage 100 without any interference alongthe axial dimension and is able to rotate without any friction caused bysurfaces contacting each other forcibly along the lengthwise direction.

In embodiments of the invention, the ends of shaft 210 of spin-plate 200may be flat-ended as illustrated or may have a convex curvature. Opening150 and opposed concave feature 160 could be either flat-bottomed orconcavely-curved.

In embodiments of the invention, the spin-plate 200 may be captured inthe spinal cage 100 by one or both of two types of capturing action. Itis possible that one of the capturing actions may be in effect evenbefore the spin-plate 200 has been rotated away from the angularorientation that it has during insertion into spinal cage 100.

Another possibility is that there may be a capturing action that is ineffect only for some rotational positions of spin-plate 200 relative tospinal cage 100 but not for other rotational positions. It is furtherpossible that both types of capturing action may be present in theassembly.

In embodiments of the invention, the spin-plate 200 near at least oneend may have at least one flat having a local flat external width of thespin-plate 200 relative to the flat, and the spinal cage may have atleast one groove 150, 160 having a groove internal width, and the flatexternal width may be less than or equal to the groove internal width.

More generally, near at least one end the spin-plate 200 may comprise anon-circular cross-section having, at various lines passing through thespin-plate rotational axis perpendicular to the spin-plate rotationalaxis, a smallest cross-dimension and a largest cross-dimension. In sucha situation, the spinal cage 100 may comprise a generallylongitudinally-oriented groove 150, 160 having a groove width, and thegroove width may be intermediate between the smallest cross-dimensionand the largest cross-dimension. Groove width may refer to the minimumwidth dimension of the groove. For example, the spin-plate cross-sectionnear at least one end of the spin-plate could be elliptical. Thespin-plate cross-section near at least one end could be thecross-section of an enlargement 250, 252 or could be a cross-section ofthe shaft 210 itself of spin-plate 200.

In embodiments of the invention, the spin-plate 200 and the spinal cage100 may cooperate to provide at least one detent position in therotation of the spin-plate 200 with respect to the spinal cage 100. Thedetent may be such that rotation past the detent is permitted, but acertain amount of torque is necessary to pass the detent position, withthat certain amount of torque being larger than the amount of torqueneeded to produce rotation in other portions of the rotational sequence.It is possible that there can be two detent positions in rotation of thespin-plate 200 with respect to the spinal cage 100. The two detentpositions may separated by approximately 90 degrees of rotation, or byapproximately 180 degrees of rotation. It is possible that a detentposition can correspond to the deployed configuration of the spin-plate200 relative to the spinal cage 100, in which blade 230 extends beyondspinal cage 100. It is possible that a detent position can correspond tothe undeployed configuration in which blade 230 is contained withinspinal cage 100. If there are two detent positions, it is possible thatthey can correspond to both of the just-described configurations.

In embodiments of the invention, it is also possible that the spin-plate200 and the spinal cage 100 may cooperate to provide at least one stopposition in rotation of the spin-plate 200 with respect to the spinalcage 100. In such a structure, when rotation reaches an appropriateposition for the stop condition to come into effect, then the spin-plate200 may become immobilized with respect to the spinal cage 100, it maybecome extremely difficult or impossible to rotate the spin-plate 200beyond the stop angular position. It is possible that when the stopposition is reached, it may still be possible to rotate the spin-plate200 backward from the stop position. It is further possible that theremay be a detent at the stop position, such that reverse rotation fromthe stop position requires overcoming a threshold amount of torque. Itis still further possible that the spinal cage assembly could have aratchet feature.

In embodiments of the invention, the spin-plate 200 and the spinal cage100 may cooperate to provide an audible sound upon achievement of atleast one particular angular position in rotation of the spin-plate 200with respect to the spinal cage 100. The audible signal can come fromsome form of slippage of a member relative to another member. It ispossible that a mechanism that provides some other describedfunctionality, such as a detent or a rotational locking action, couldalso provide audible indication of an action or a condition. It isfurther possible that there can be tactile feedback that can be felt bythe hand operating the tool or instrument that rotates the spin-plate200. This tactile feedback can comprise, for example, a sharp change inthe torque needed to rotate spin-plate 200 with respect to spinal cage100. This tactile feedback can occur upon achievement of at least oneparticular angular position in rotation of the spin-plate 200 withrespect to the spinal cage 100.

In embodiments of the invention, it is possible that the spinal cage 100and the spin-plate 200 or other deployable member may have differentradiopacities. For example, the spinal cage 100 may be made entirely ormostly of radiolucent material such as a polymer (for example,polyetheretherketone (PEEK)). If the spinal cage 100 is made of such aradiolucent material, the spinal cage 100 could additionally compriseradiopaque markers placed in it at desired locations. In such asituation, the spin-plate 200 could be made of or could comprise metal,with metals in general being at least somewhat radiopaque. As discussedelsewhere herein, it is possible that the spin-plate 200 could comprisesubcomponents that themselves have differing radiopacities. For example,the shaft 210 and the blade(s) could be made of different materialshaving unequal radiolucency or radiopacity. It is possible that thespinal cage could comprise a majority of non-metallic material and thedeployable member could comprise a majority of metal. For example, thespinal cage could be entirely polymeric material and the spin-plate 200could be entirely metallic. The spin-plate 200 or blade or deployablemember, or the spinal cage, could comprise features having knowndimensions or spatial relationships or separation distances so as to beuseful as reference and measurement markers for use during radiography.

In some embodiments of the present invention, spinal cage 100 andspin-plate 200 may comprise features that cooperate with each other toprovide detents or stops involving the rotation of spin-plate 200relative to spinal cage 100. Such features are illustrated in FIGS. 8,9, 10, 19 and others.

In more detail, spinal cage 100 may comprise posts 190 that may protrudefrom the body of spinal cage 100 in an interior-facing direction.Spin-plate 200 may comprise geometric features that are appropriatelylocated so as to interact with the posts 190. Spin-plate 200 maycomprise disc 290, which may extend radially outward away from thelongitudinal axis of shaft 210 of spin-plate 200. Disc 290 may comprisepeaks or high regions that are more radially distant from the axis ofspin-plate 200, and valleys or low regions that are closer to the axisof spin-plate 200. A peak or high region can include a plateau regionhaving a substantially constant radial dimension, and a valley or lowregion also can include a region having a substantially constant radialdimension.

It is possible that the portion of post 190 that protrudes beyond thesurface of wall 110 into interior space 112 of spinal cage 100 may havea taper. The taper may be such that the protruding part is larger incross-section closer to the internal surface of wall 110, and is smallerin cross-section further from the internal surface of wall 110. The head194 of post 190 may be frustoconical, although other shapes are alsopossible. As illustrated, the frusto-conical head 194 of post 190 has atotal cone angle of 15 degrees or a half-angle of 7.5 degrees. This isillustrated in FIGS. 8, 9, 10 and others.

As illustrated in FIG. 10, disc 290 may comprise a series of a firstvalley, a second valley and a third valley. The angular interval fromthe center of the first valley to the center of the third valley may beapproximately 90 degrees. The center of the second valley may be midwaybetween the centers of the first valley and the third valley. The firstvalley and the third valley may be defined by inward curvatures havingrespective radii of curvature that may be equal to each other (labeledas R1). The second valley may be defined by another inward radius ofcurvature that is labeled as R2. The bottoms of first valley and thirdvalley may be such that post 190 can approximately touch the bottoms ofthe first valley and the third valley, thereby providing a detent. Thebottom of second valley may be such that there is clearance betweenposts 190 and the bottom of the second valley, thereby providing freerotation. The disc 290 may further comprise an external surface that isapart from the first-second-third valley sequence, which is defined byan outward curvature whose center of curvature is not located at thecenter of rotation of spin-plate 200.

It is also possible that the perimeter of disc 290 of spin-plate 200, orsome portion of the perimeter of disc 290, can have a taper in adirection corresponding to the direction of taper of the head 194 ofpost 190. The angle of taper can be substantially equal to thehalf-angle of the frustoconical portion of post 190. However, the taperangles need not be identical to each other. It is not essential to haveany taper on either of these components 190 or 290.

In describing the interaction of post 190 and disc 290 of spin-plate200, it is useful to define a baseline distance from the center ofrotation of spin-plate 200 to the nearest edge of the head 194 of post190.

For achieving a detent, it is possible that a peak such as detent peak292 may create a slight interference with post 190, but at the same timethere may be appropriate elasticity in the spinal cage 100 or thespin-plate 200 or both so that upon application of a desired torque tospin-plate 200, detent peak 292 may slip past post 190. This can providea detent action. Alternatively, it would also be possible to achieve adetent action with spring-loaded movable parts, living hinges, or byother means.

It is also possible that a peak such as stop peak 294 may interact witha post 190 so as to completely block further rotation of spin-plate 200in a given direction beyond stop peak 294. The interference involvingstop peak 294 may be such that it is not possible, using a reasonableamount of torque, to cause stop peak 294 to slip past post 190.

It is further possible to provide both a detent action and a stop actionin close proximity to each other. In such a situation, rotation ofspin-plate 200 may be able to occur freely in a certain range, andfurther rotation may involve passing a detent that requires a certainamount of torque to overcome. Upon passing this detent, there may beencountered a stop that completely prevents further rotation in thatdirection. When the components are in this described position, noadditional forward rotation would be possible but rotation in thereverse direction would still be possible if suitable torque is exertedto pass the detent in the reverse direction.

FIG. 19 illustrates how the components can achieve certain detent andstop characteristics. As illustrated, stop peak 294 has a greater radialdimension than detent peak 292. Detent peak 292 and stop peak 294 may besufficiently close together so that post 190 nestles in the valleybetween those two features and has little or no permitted rotation whilelocated between those two features. In this configuration, while post190 is between peaks 292, 294, there may be no rotation possible in adirection that would advance beyond peak 294 using any reasonable amountof torque, but there may be rotation possible in the reverse directionif sufficient torque is exerted to pass the detent involving detent peak292.

It is also possible that there can be two detent peaks 292 in closeproximity to each other so that when post 190 nestles between those twodetent peaks 292, there is little or no permitted rotation. However,upon application of appropriate torque, it is possible to pass thedetent in either direction of rotation.

It is possible that there may be a detent peak 292 plus a nearby detentpeak 292 in close proximity to each other for a position thatcorresponds to the stowed position of spin-plate 200 in which deployableelements do not protrude from spinal cage 100, as may be used during theinitial implantation action. There may also be a detent peak 292 alongwith a nearby stop peak 294 in close proximity to each other for aposition that corresponds to the deployed position of spin-plate 200 inwhich deployable elements protrude from spinal cage 100, as may be usedduring the final part of implantation. The undeployed (stowed) positionand the deployed position may be separated from each other byapproximately 90 degrees of rotation. In the illustrated configuration,at the stowed position, there is a detent action, and at the deployedposition, there is a detent with stop action. The detent plus stopaction prevents rotation of the spin-plate further than the deployedposition.

It is possible to have more than one detent or more than one stop suchthat the same detent action or stop action is created simultaneously attwo different locations around the perimeter of disc 290. This may beachieved in conjunction with having two posts 190. These two locationsof posts 190 may be separated from each other by approximately 180degrees of angular position. The described configuration of two detentpeaks 292 in close proximity to each other may occur at two placesaround the disc 290. Similarly, the described configuration of a detentpeak 292 in close proximity to a stop peak 294 may occur at two placesaround the disc 290. The use of such duplicative configurations mayprovide redundancy. If there is a plurality of detent peaks 292, thevarious detent peaks 292 may be geometrically identical to each other,but they do not have to be. If there is a plurality of stop peaks 294,the various stop peaks 294 may be geometrically identical to each other,but they do not have to be.

FIG. 19 b illustrates another possible shape of disc 290. In thisspin-plate there is an especially tall stop peak 294. FIG. 19 aillustrates the same also showing the positions of post 190 when thespin-plate is in position such that blade is undeployed (neutralposition). A configuration such as this can ensure that rotation awayfrom the stowed position is only possible in one direction of rotation,and also that the rotation encounters a well-defined stop at theintended end of rotation. At the stowed position, there is a detentaction with a stop that prevents the spin-plate from rotating further inthe reverse direction than the stowed position. In the configuration ofFIG. 19 c at the deployed position, there is a detent with stop actionthat prevents rotation of the spin-plate 200 further than the deployedposition.

Referring now to FIGS. 9, 10, 18, and 19, the disc 290 may comprise aseries of three valleys that govern motion over a rotational interval of90 degrees. This same pattern may be repeated 180 degrees away on thedisc 290. The first valley may be where post 190 nestles in the stowedposition of blade 230. The third valley maybe where post 190 nestles inthe deployed position of blade 230. The bottom of the first valley andthe bottom of the third valley may be separated from each other by 90degrees of rotation. The bottom of the first valley and the bottom ofthe third valley may be at the same radial distance from the axis ofrotation of spin-plate 200, although they do not have to be. The bottomof the second valley may be deeper (at a smaller radial distance fromthe axis of rotation) than the bottom of the first and third valleys,which could allow for relatively free rotation of spin-plate 200 duringmuch of the rotation from the stowed position to the deployed position.However, it is not essential that the bottom of the second valley bedeeper than the bottom of the first and third valleys. At the edge ofthird valley that is beyond the position that post 190 would travel induring the nominal 90 degrees of rotation, i.e., that is away from firstand second valleys, the wall of the third valley may rise higher thandoes the wall of the first valley on the side of the first valley thatis away from second and third valleys. This extra wall height mayprovide an especially secure stop action to prevent the spin-plate fromrotating beyond the desired 90 degrees of rotation. The described sideof first valley may be high enough to provide a detent action, but notas high as the described height of the third valley wall, in order tohelp allow the spin-plate to slide into position through the groove 160.

Both the anterior tip of the spin-plate 200 and the posterior tip of thespin-plate 200 may have a pair of opposed flats, and sliding-in to thegrooves in spinal cage 100 may be guided by using the flat. After thespin-plate 200 has slid through the grooves 150, 160 and into opening120, opposed concave feature 130 suitably far that it is able to rotate,and after a small amount of rotation has taken place, one or both tipsof spin-plate 200 may become trapped in opening 120 or opposed concavefeature 130 thereby resisting any force that might tend to dislodgespin-plate 200 from that position.

Another embodiment of the invention is illustrated in FIGS. 30 and 31Aand 31B. In this embodiment, there is again provided a spinal cage 100and there may be provided a spin-plate 200 that can optionally beinserted into spinal cage 100. FIG. 30 is a perspective view of thespinal cage 100 alone, and many of its features have been describedelsewhere herein. Spinal cage 100 may comprise two holes 176A, 176B.Features may be arranged so that along the front or anterior surface ofspinal cage 100, there is hole 176A, opening 120, and hole 176B. Holes176A, 176B may be symmetrically located with respect to opening 120 orwith respect to a sagittal plane of spinal cage 100. Holes 176A, 176Bmay have respective axes that are directed at specified compound anglesthrough the front wall of spinal cage 100. Hole 176A may have a holeaxis 178A and hole 176B may have a hole axis 178B. FIG. 31A illustratesthe configuration of the assembly when the spin-plate 200 is assembledto spinal cage 100 and is undeployed. In the configuration of FIG. 31A,these holes 176A, 176B are at least partially blocked by the blade 230of spin-plate 200. For example, in FIG. 31A, a portion of blade 230 canbe seen to partially obstructs hole 176A. FIG. 31B illustrates theconfiguration of the assembly when the spin-plate 200 is assembled tospinal cage 100 and is in the deployed position. In this configuration,there is access to insert bone screws through holes 176A, 176B. Thissame configuration is further illustrated in FIGS. 32A, 32B and 32C,which are front, top and side views respectively of the assembly, butwith the spin-plate omitted for clarity of illustration.

In this embodiment, with respect to the longitudinal direction of spinalcage 100, holes 176A, 176B in spinal cage 100 may be directed away froma central portion of spinal cage 100 toward adjacent vertebrae. One ofthese axes 178A, 178B is directed from the spinal cage 100 cephaladlyand the other of these is directed from the spinal cage 100 caudally. Asillustrated, the angle by which each of hole axes 178A, 178B is directedaway from a midplane of spinal cage 100 (which roughly corresponds to anaxial plane of a patient's body) (labeled alpha in FIG. 32C) is 45degrees for each hole axis 178A, 178B relative to the midplane. Asillustrated, hole axes 178A and 178B also have an angle with respect toa plane of symmetry of the spinal cage 100 that is another plane ofsymmetry of the spinal cage 100 and roughly corresponds to a sagittalplane of a patient's body. As illustrated, this angle (labeled beta inFIG. 32B) is 19 degrees pointing inward toward the plane of symmetry foreach hole axis 178A, 178B relative to the plane of symmetry. Of course,it may be understood that other values for angles alpha and beta arealso possible.

Referring now to FIGS. 33A, 33B, 34A and 34B, associated with holes176A, 1760B there may be respective cage shoulders 180A, 180B. Cageshoulders 180A, 180B may be coaxial with respective holes 176A, 176B andmay be dimensioned suitably to receive a head 185A, 185B of a bone screw182A, 182B as described elsewhere herein. Cage shoulders 180A, 180B maybe deep enough so as that the head 185A, 185B of bone screw 182A, 182Bcan reside within cage shoulders 180A, 180B without protruding beyondthe surface of spinal cage 100. In addition, recessed within cageshoulders 180A, 180B there may be cage grooves 188A, 188B. Cage grooves188A, 188B may be suitable to receive a snap-ring 194 as describedelsewhere herein.

Additionally there may be provided bone screws 182A, 182B. Bone screws182A, 182B may be suitable to engage bone and may comprise a head 185A,185B and a shaft 186A, 186B, which may have threads 187A, 187B. Head185A, 185B may be of larger outside diameter than the major diameter ofthreads 187A, 187B and may comprise a screw shoulder 188A, 188B wherehead 185A, 185B meets shaft 186A, 186B. Head 185A, 185B may comprise ascrew groove 189 that may be suitable to receive a snap-ring 194therein. Bone screws 182A, 182B may comprise a tool-receiving featuresuch as a hexalobe, for receiving a tool to rotate the bone screw. Bonescrews 182A, 182B may comprise a self-tapping feature on the end ofthreads 187A, 187B away from heads 185A, 185B.

Details of bone screw 182A, 182B, snap-ring 194, and various geometry inthe spinal cage 100 may be similar to those described in U.S. Pat. No.7,001,389, which is hereby incorporated by reference in its entirety. Inparticular, snap-ring 194 may comprise a leading external corner 195that is rounded, and a trailing external corner 196 that is sharper thanleading external corner 195. For use, snap-ring 194 may be providedinstalled in screw groove 189 in screw 182A, 182B with the describedorientation of leading external corner 195 and trailing external corner196. This is illustrated in FIGS. 35A, 35B. In regard to FIG. 35B, itmay be noted that the absence of screw 182A, 182B from FIG. 35B is onlyfor sake of clarity.

FIG. 34A and FIG. 34B also illustrate thread 199 internal to hole 176A,1760B. It is possible that spinal cage 100 may be designed to be usedwith both a nominal dimension screw and a screw having threads that arelarger in some dimension, which may be called a “rescue screw.” A“rescue screw” may be used during surgery if the nominal screw does nothave sufficient grip with the bone. It is possible that the internalthreads 199 and the dimensions of the various screws may be such thatthe nominal screw can pass through the hole 176A, 1760B without engagingthreads 199, whereas when the rescue screw passes through hole 176A,1760B the external threads of the rescue screw do engage the internalthreads 199 of hole 176A, 1760B.

The geometric relationship between spinal cage 100, spin-plate 200 andbone screws 182A, 182B may be such that when spin-plate is in its stowedposition, bone screws 182A, 182B cannot be placed through holes 176A,176B (as illustrated in FIG. 30), due to blade 230 of spin-plate 200 atleast partially blocking holes 176A, 176B. On the other hand, whenspin-plate 200 is in its deployed position, bone screws 182A, 182B maybe placed through holes 176A, 176B (as illustrated in FIG. 31), becausein that situation blockage of holes 176A, 176B by blade 230 maybenonexistent or at least may be sufficiently small to allow the passageof the screws through holes 176A, 176B. When the spin-plate 200 is in anundeployed position, the spin-plate 200 may cover at least a portion ofscrew holes 176A, 176B, and when the spin-plate 200 is in a deployedposition, the spin-plate 200 may cover none of the screw hole 176A, 176Bor less of the screw hole 176A, 176B than when the spin-plate 200 is inthe undeployed position.

Given the various choices and constraints described herein, there areseveral possibilities for how to implant the described apparatus in apatient: spinal cage only; spinal cage with bone screws but nospin-plate; spinal cage plus spin-plate, without bone screws; and spinalcage plus spin-plate plus bone screws. A choice among thesepossibilities may be made by the surgeon during or just slightly beforesurgery, given the fact that the spin-plate is easily insertable intothe spinal cage and can even be easily removed from the spinal cage,when the assembly is outside the patient's body, if there is a need todo so.

Referring now to FIGS. 20-25, the installation tool may haveconstruction comprising two or three members that are at leastapproximately coaxial with each other and are nested within each other.The outermost member may, at its distal end, engage a spinal cage 100.The spinal cage 100 may be a spinal cage or the like. As illustrated inFIG. 21, a portion of the installation tool such as the outermost memberof the installation tool may, for example, comprise a protrusion that issuitable to engage an external feature of spinal cage 100 such asinstrumentation groove 174. Another member of the installation tool,such as the intermediate member of the installation tool, may, at itsdistal end, engage an instrumentation interface feature of spinal cage100. For example, this member may comprise, at its distal end, threadsthat may be capable of engaging corresponding threads on spinal cage100, such as threads in openings 172 a, 172 b, 172 c, 172 d. Takentogether, these two members may engage spinal cage 100 so as to providea substantially rigid connection between the installation tool andspinal cage 100. One of the members may have a thumbwheel at or near itsproximal end.

The installation tool may further comprise a member that, at its distalend, is capable of interfacing with spin-plate 200, which may berotatable with respect to spinal cage 100. This member, which may bereferred to as a locker tool, may be insertable into the rest of theinstallation tool or removable therefrom, as desired. It is possiblethat when the locker tool is not in its operable position, the remainingpart of the installation tool may be capable of being struck by ahammer. FIG. 23 illustrates a locker tool by itself. FIG. 24 illustratessuch a tool ready to be inserted in the installation tool.

It is still further possible that the mechanism for causing rotation ofthe spin-plate 200 may have some portion that is permanently part of theinstallation tool and some other portion that is connected to theinstallation tool only when desired. The innermost member may comprise afirst part and a second part. The first part may be capable of engagingwith and rotating spin-plate 200. The second part may be connectable tothe first part and may comprise a handle. The second part may beremovable from the installation tool. When the second part is absentfrom the installation tool, the installation tool may be capable ofbeing struck on its proximal end by a hammer or similar device, whilethe installation tool is engaged to spinal cage 100.

It is possible that a handle or other feature of the locker tool (ormore generally any device that causes rotation of the spin-plate 200)may indicate the position of the blade 230 of spin-plate 200, such as bybeing parallel with the blade 230 of spin-plate 200. FIG. 25 a shows aspinal cage assembly together with the installation tool and lockertool, in a configuration such that the blade 230 is in a neutral orundeployed position. As illustrated, blade 230 and the handle of thelocker tool are substantially parallel to each other in a substantiallyhorizontal orientation. FIG. 25 b shows the same apparatus in a deployedor engaged configuration. Again, blade 230 and the handle of the lockertool are substantially parallel to each other, but in this illustrationboth have a substantially vertical orientation. These illustrationsillustrate the configuration that would be used for an anterior surgicalapproach.

The insertion tool may be either combined with or separate from arotational tool that may be used for rotating the spin-plate 200. Thehandle of the tool for rotating the spin-plate could be parallel to thelong direction of the spin-plate 200. This could provide a directindication to the surgeon of the position of the spin-plate 200.

It is possible that the installation tool may comprise limits onrotation of the innermost member, relative to other parts of theinstallation tool. The installation tool may be designed and constructedsuch that, when the installation tool is engaged with spinal cage 100,the initial rotational limit or the final rotational limit or both maysubstantially correspond to the situation in which spin-plate 200 is ata rotational detent or a rotational stop that may be built into therelationship between spin-plate 200 and spinal cage 100 when spin-plate200 is installed in spinal cage 100. It is further possible that theinstallation tool may comprise a ratchet such as to determine that onlyone direction of rotation is allowable, rather than both directions ofrotation.

Referring now to FIGS. 20-25, in some embodiments of the presentinvention, there may be provided an installation tool 710 that mates tospinal cage and has a central passageway 715 able to accept a rotationaltool 720 for rotating spin-plate 200. The installation tool 710 thatmates with spinal cage 100 may be physically separate from therotational tool 720 that is used to rotate spin-plate 200 and may beable to be used independently of the rotational tool 720 that is used torotate spin-plate 200. It is possible to insert spin-plate rotation tool720 through the bore 715 of installation tool 720 at desired times andto remove spin-plate rotation tool 720 from the bore 715 of installationtool 710 at other times when it is not desired to use the toolstogether. For example, in some embodiments of the present invention,there may be times when the spinal cage 100 is implanted withoutcontaining spin-plate 200. In such instance, there is no need forspin-plate rotation tool 720. In other situations, when the spin-plate200 is in the spinal cage 100, there still may be times during surgerywhen there is no need for the presence of the spin-plate rotation tool720, and so the spin-plate rotation tool 720 can be absent at thosetimes. Such absence may free up the bore of the installation tool 710for other purposes.

Furthermore, in some embodiments of the present invention, it ispossible that the instrumentation used for causing rotation ofspin-plate 200 may be designed such that the instrumentation itself onlyallows the designated amount of rotation, such as 90 degrees, and theinstrumentation makes it impossible to over-rotate spin-plate 200 beyondthat designated amount of rotation beyond the designated amount ofrotation.

FIGS. 22 a, 22 b, 22 c, 22 d illustrate the assembly of an installationtool to the spinal cage 100 in for different orientations for fourdifferent surgical approaches.

An embodiment of the invention comprises a kit containing at least onespinal cage 100 and at least one spin-plate 200 suitable to fit into atleast one of the spinal cages 100. It is possible that various spinalcages 100 in the kit may differ from each other in lordosis angle, inoverall dimensions, or any other respect. However, it is also possiblethat even if various spinal cages 100 differ from each other in somerespect, all or some of the spinal cages 100 could still be identical inthose dimensions or features that affect the interaction of spin-plate200 with spinal cage 100. It is possible that various spin-plates coulddiffer from each other in the position of the blade 230 on shaft 210,such as the position of blade 230 in the direction along the length ofthe blade 230. In such a situation, the spin-plate 200 could be chosenat or around the time of surgery based on what location within the bone(cortical bone as compared to cancellous bone, or how far into the bonein a direction along the anterior-posterior direction that is the axisof rotation of spin-plate 200) it is desired that the spin-plate 200interact with. The kit and its components could be made such that morethan one spin-plate 200 is suitable to be used with a particular spinalcage 100. For example, it is possible that a particular spinal cagecould accept more than one choice of spin-plate 200, each of which mighthave different tip-to-tip length of blade 230, thereby providing choicesas to the distance of penetration of blade 230 into adjacent vertebrae.

The kit may further comprise tools for installing, measuring or othercapabilities. If any tools are associated with placing the spin-plate200 into spinal cage 100, such tools can be included in the kit.

Embodiments of the invention may comprise a kit containing at least onespinal cage 100, and at least one spin-plate 200 mateable with spinalcage(s) 100 at the option of the surgeon at the time of the operation,and at least one bone screw 182A, 182B insertable through spinal cage100 at the option of the surgeon at the time of the operation. Thegeometric relationships between the spinal cage 100, the spin-plate 200and the bone screws 182A, 182B may be as described elsewhere herein. Thekit may comprise more than one of any of the items as desired, and maycomprise more than one size or design variation of any of the items asdesired. The kit may contain multiple spinal cages, which may vary infootprint dimension, height, lordosis angle, and any other featuresdesired. The kit may contain multiple spin-plates, which may vary inblade length which in turn may affect the degree of penetration intovertebral bone. The kit may contain multiple bone screws 182A, 182B thatvary in length, thread characteristics, or other features, and it isfurthermore possible to provide a “rescue screw” that is slightly largeror more engaging than the standard screw, for use in the event that thestandard screw does not sufficiently engage with local bone.

Some embodiments of the present invention may comprise a filler piece600 suitable to occupy a large fraction of the open space in theinterior of spinal cage 100 that is not already occupied by thespin-plate 200. This is illustrated in FIG. 26. If the spinal cage 100is used with spin-plate 200, the filler piece 600 may have empty spacessuitable to accommodate any permissible rotational position ofspin-plate 200.

Geometrically, the filler piece 600 may be dimensioned such that whenthe filler piece 600 is in place, the filler piece 600 does not occupyany space occupied by the shaft 210 of the spin-plate 200 and also doesnot occupy any space occupied by the blade 230 of the spin-plate 200 inany of the positions that the spin-plate 200 either is permitted tooccupy or passes through during permitted rotation. It is still possiblethat the filler piece could occupy certain space that is in the plane ofrotation of spin-plate blade 230 but is located at rotational angleswhere the blade never goes. Also, the filler piece 600 may bedimensioned such that when the filler piece 600 is in place, the fillerpiece 600 does not occupy any space occupied by the disc 290 that may benear the posterior end of the shaft 210 of the spin-plate 200.

The filler piece 600 may comprise a slot 610 opening to one of the endface surfaces of the filler piece 600. Slot 610 may have a width atleast as large as the diameter of the shaft 210 of the spin-plate 200.The geometry of the slot 610 and the other dimensions of the fillerpiece 600 may be such that when the spin-plate 200 is in place in spinalcage 100 and the filler piece 600 is in place in spinal cage 100, theend face surfaces 620 of the filler piece 600 may at least approximatelyalign with end surfaces of the spinal cage 100 itself.

Regarding other surfaces of filler piece 600, the filler piece 600 maybe such that when the filler piece 600 is in place in spinal cage 100, aposterior face 630 of the filler piece 600 touches an internal posteriorsurface of spinal cage 100. The filler piece 600 may further be suchthat when the filler piece 600 is in place in the spinal cage 100 withthe posterior face 630 touching internal posterior surface of spinalcage 100, filler piece 600 does not interfere with the spin-plate 200 orblade 230 in any of the permitted positions of rotation. The location offiller piece 600 may be defined in part by having the front surface offiller piece 600 touch blade 230 or be able to fit between blade 230 andthe internal posterior surface of spinal cage 100. Alternatively, theremay be constraints such that filler piece 600 contacts the interior ofspinal cage 100 in such a way that insert 600 is constrained againstmoving into any position that would result in interference withspin-plate 200 or blade 230. For example, the constraint may be suchthat filler piece 600 cannot advance sufficiently far anteriorly even totouch blade 230. For example, a portion of a front surface 640 of fillerpiece 600 may interact with an internal surface of spinal cage 100 so asto insure that there is some empty space between filler piece frontsurface 640 and the corresponding internal surface of spinal cage 100.It is possible that filler piece 600 could be shaped so that whenposterior face 630 touches internal posterior surface of spinal cage100, a portion of anterior face of filler piece 600 touches or nearlytouches an internal anterior surface of spinal cage 100, in a place thatis not within the range of motion of blade 230 in any of the permittedpositions of blade 230.

Filler piece 600 may further comprise a recess 690 suitable toaccommodate a disc 290 on spin-plate 200. For example, recess 690 may bea groove.

The filler piece 600 may be porous and conducive to bone ingrowth. Thefiller piece 600 may be substantially rigid or alternatively may havesome property of elasticity or ability to be squeezed. The filler piece600 may be osteoconductive, such as comprising a member of the calciumphosphate family and having pores of appropriate size. The filler piece600 may further be osteoinductive, such as comprising any of a number ofknown osteoinductive substances, such as but not limited todemineralized bone matrix, bone morphogenetic protein, and other knownsubstances. The filler piece 600 may contain blood, bone marrow,platelet rich plasma, or other such substances. The filler piece 600 maybe resorbable and may comprise one or more resorbable polymers and maycomprise a resorbable or nonresorbable ceramic.

The filler piece 600 may be resilient, such as a filler piece 600 thatcomprises particles of ceramic joined by films of a polymeric materialthat is at least somewhat resilient. The filler piece 600 may beslightly larger in the longitudinal direction than the correspondingdimension of spinal cage 100 so that when an assembly of a spinal cage100 and filler piece 600 is implanted in a patient, the filler piece 600establishes contact against endplate or bone of vertebrae. The abilityof a resilient filler piece 600 to compress may allow the assemblycomprising spinal cage 100 and filler piece 600 to be installed so thatthe filler piece 600 is slightly in compression between the vertebrae.That compression may help to maintain contact between the vertebralendplate and the filler piece 600, aiding in ingrowth of bone into thefiller piece 600. It is also possible that the filler piece 600 may bein compression between certain surfaces of the interior of the wall 110of spinal cage 100. This may help to keep the filler piece 600 in placerelative to the spinal cage 100 during implantation or other steps.

It is possible for a kit to contain a first filler piece 600 suitable tobe used when a spin-plate 200 is installed in spinal cage 100, and alsoa second different filler piece suitable to be used if spinal cage 100is installed without containing a spin-plate 200. In this way, thefiller piece 600 used in the presence of a spin-plate 200 provides amaximum amount of filler or bone growth promoting material that can beused under the circumstances when a spin-plate 200 is present, and forthe situation where no spin-plate is present, the internal cross-sectionof the spinal cage 100 can be essentially completely filled with adifferent filler piece.

It is possible that the filler piece 600 may have a specific color. Inorder to accomplish this, the filler piece 600, at one of the laststages of manufacturing, may be wetted with a solution containing abiocompatible dye. Then, the solvent of that solution may be allowed orcaused to evaporate, leaving the dye behind in filler piece 600. Thesolution may be aqueous, or may be based on an organic solvent such asethanol, or could contain both water and an organic solvent such asethanol. The dye may be a dye that is water-soluble, ororganic-solvent-soluble, or both. The solution could also comprise asurfactant. It is furthermore possible that the coloration could beapplied only to specific regions of the filler piece 600, rather thaneverywhere.

A surgeon may be provided with a set of spinal cages and installationtools any or all of which may use color-coding. Color-coding of metalparts such as spin-plates 200 or instrument tips may be achieved byanodizing or other surface treatment. Color-coding of polymeric partssuch as spinal cages 100 may be achieved by additives during molding.Color-coding of filler pieces 600 may be achieved as described.

For example, a spinal cage 100 and the filler piece 600 intended forthat spinal cage 100 may have identical or similar colors.

In some embodiments of the present invention, the spinal cage 100 maycomprise a radiopaque marker that also interacts with a deployableelement or a rotatable element such as spin-plate 200. For example, theradiopaque marker may be a post 190 that may be involved in creating adetent function or a stop function or both involving rotation ofspin-plate 200. Post 190 is illustrated in FIG. 8. The radiopaque markermay be more radiopaque than other parts of the spinal cage 100. It isfurther possible that there may additionally be other radiopaque markerspresent in spinal cage 100 that do not interact with a deployable orrotatable element such as spin-plate 200. Radiopaque markers may belocated so as to assist in interpreting radiographic images and may belocated in more than one plane or direction. For example, post 190 maybe made of or may comprise a material having a desired radiopacity.

Some embodiments of the present invention can include a trial piece thatmay be geometrically similar to the actual spinal cage but not intendedto remain inside a patient. A trial piece may comprise a spin-plate 200with a blade 230 similar to those in the actual spinal cage assembly. Itis possible that a trial piece could have a blade 230 that is strongerthan the blade 230 in the actual spinal cage assembly.

It is possible that a trial piece could be made out of metal rather thanthe polymeric material that might be used for the actual spinal cage100. It is also possible that a trial piece might have smoothvertebra-facing surfaces rather than having grooves or teeth as might bepresent on the actual spinal cage 100. Such a lack of teeth might makeit easy to remove the trial piece when it is time to implant the actualspinal cage 100.

A trial piece could be used if a deployable element such as a blade 230is resorbable, which brings the possibility that a resorbable blade 230might not be as strong as a blade made of metal. This might create anincentive to use a separate trial piece to cut a slot in the bone. Forexample, a trial piece that is made completely out of metal includingthe blade could be stronger than the actual spinal cage assembly andmight be capable of receiving more torque or exerting more cutting forcethan the actual spinal cage assembly. It would be possible to use such atrial piece to pre-cut a slot that may be the interface for the actualspinal cage. Then, the trial piece could be removed and the actualspinal cage assembly could be implanted appropriately located so thatthe blade 230 of the actual spinal cage enters the slot in bone createdby the blade of the trial piece.

Some embodiments of the present invention can comprise the surgicalmethod described herein. The method can include: implanting a trialpiece having a trial piece deployable member; deploying the trial piecedeployable member so as to displace or remove bone to form a cavity;retracting the trial piece deployable member; removing the trial piece;implanting a spinal cage assembly having a deployable member; anddeploying the deployable member to occupy at least a portion of thecavity created using the trial piece.

Some embodiments of the present invention comprise a surgical method.

It is described elsewhere herein that one possible surgical approach forimplantation of the described spinal cage assembly is an anteriorapproach. However, it is also possible that the spinal cage assemblycould be implanted using a surgical approach that is other than ananterior approach. For example, the approach for implanting the spinalcage assembly could be lateral or anterolateral. However, even if spinalcage assembly is implanted via some surgical approach other thananterior, the axis of rotation of spin-plate 200 may still beanterior-posterior. Therefore, causing the spin-plate 200 to rotate intoa desired angular position may involve accessing a feature that is on ananterior surface of the spinal cage 100, which may require some use ofan anterior approach.

In yet another embodiment of the invention concerning a surgical method,the surgical method may include implanting a spinal cage that comprisesfeatures for accepting a spin-plate therein, and also comprises at leastone hole for accepting a bone screw, as illustrated in FIGS. 30-35. Thesurgical method may comprise any of the following: implanting the spinalcage alone; implanting the spinal cage containing a spin-plate, followedby rotating the spin-plate; implanting the spinal cage followed byinserting screws; or implanting the spinal cage containing a spin-plate,followed by rotating the spin-plate, followed by inserting screws.

In yet another embodiment of the invention concerning a surgical method,the surgical method may include implanting, by a lateral approach, aspinal cage 1100 and spin-plate 1200 assembly as illustrated in FIGS.36-40, followed by rotating the spin-plate 1200.

A surgical method may comprise using two separate incisions asillustrated in FIG. 27. The incision for implanting the spinal cageassembly may be an incision using an approach other than an anteriorapproach and may be the larger of the two incisions. The incision forcausing rotation of spin-plate 200 may be the smaller of the twoincisions and may be an anterior approach. For example, the spinal cageassembly may be installed using an anterolateral or lateral approach,and then for purpose of causing rotation of spin-plate 200, a smallincision using approximately an anterior approach may be created toprovide access for a rotational tool.

FIGS. 28 and 29 illustrate spinal cage assemblies that contain gears tore-orient rotational motion delivered to the spinal cage assembly by atool. In FIG. 28 there is a worm gear, and in FIG. 29 there is a bevelgear.

Yet another embodiment of the invention is illustrated in FIGS. 36-40.This embodiment may be particularly suited for implantation into apatient using a surgical approach that is at least approximately alateral surgical approach. In this embodiment, there may be provided aspinal cage 1100, wherein the spinal cage 1100 has a wall 1110 extendingin a longitudinal direction and forming a closed curve or perimeter in aplane that is perpendicular to the longitudinal direction of the spinalcage 1100. Further, connected to the wall 1110 internally in two placesmay be a rib 1120 connecting a first point or location 1112 on the wall1110 with an opposing point or location 1114 on the wall 1110. Points orlocations 1112, 1114 may each be located somewhere near the middle of along dimension of spinal cage 1100 but need not be located exactly atthe middle. The two cavities into which the rib 1120 divides theinterior space need not be identical to each other or symmetric witheach other.

The spinal cage 1100 may have a long dimension and a short dimensionthat may correspond to the shape of a disc space in a human spine. Thewall 1110 may also have a post 1190 protruding therefrom into theinterior of the spinal cage 1100. The post 1190 may be located near anextreme end of the wall 1110 along the long dimension of the outline ofwall 1110. The post may have a frustoconical head and may have acylindrical body that embeds itself into wall 1110, similar to post 190described elsewhere herein for other embodiments.

There may further be provided a spin-plate 1200 having a shaft 1210 anda blade 1230, such that the shaft 1210 has a first end and a second endof the shaft 1210 opposed to the first end. The spin-plate may furthercomprise disc 1290. Disc 1290 may interact with post 1190 to producedetents and stops involving the rotation of spin-plate 1200 relative tospinal cage 1100, similarly to what is described elsewhere herein forother embodiments. In FIGS. 37, 38, 39 and 40 there is illustrated onlyone frustoconical post 1190, in contrast to two such posts 190illustrated in other embodiments. It is possible that only one post 1190may be provided due to space limitations. The use of only one such post1190 may provide efficient utilization of the space available withinspinal cage 1100. In this embodiment in FIGS. 38 and 39, it isillustrated that when spin-plate 1200 is installed in spinal cage 1100,a surface of blade 1230 is close to or touching a surface of rib 1120.However, other positions of blade 1230 along shaft 1210 are alsopossible, as is true also for positions of blade 230 along shaft 210 inother embodiments. It is possible that when spin-plate 1200 is installedin spinal cage 1100, there may be a slight gap between disc 1290 and thenearby internal surface of spinal cage 1100, as illustrated in FIG. 45,but other designs are also possible.

The wall 1110 may have a first feature 1150 for receiving the first endof the shaft 1210 of the spin-plate, and the rib 1120 may have a secondfeature 1160 for receiving the second end of the shaft 1210 of thespin-plate 1200. Features 1150, 1160 may be analogous to respectivefeatures 150, 160 described elsewhere herein for other embodiments.However, feature 1160 may be a slot, and need not be a groove, i.e., itmay have sidewalls but need not have a bottom or a base surface.Alternatively, second feature 1160 could have a bottom. The absence of abottom (i.e., a through-slot) is shown in FIG. 38A, and FIG. 43 showsthe presence of a bridging member 1178 creating a bottom of secondfeature 1160. As a general description, in rib 1120 there may be acutaway feature, which may be second feature 1160. It may further bedescribed that cutaway feature may comprise a central cutaway region1121 and a connection cutaway region 1122, with the connection cutawayregion 1122 connecting the central cutaway region 1121 with an externalsurface of the rib 1120, and the connection cutaway region may have alongitudinal direction from the central cutaway region 1121 to anexterior of the rib 1120 and may have a transverse direction orthogonalto the longitudinal direction, and the connection cutaway region 1122may have a minimum width in the transverse direction and the centralcutaway region 1121 may have a maximum width in the transversedirection, wherein the minimum width of the connection cutaway region1122 is smaller than the maximum width of the central cutaway region1121. The cutaway feature may be either a cutaway feature entirelythrough the rib 1120 as illustrated in FIG. 38A, or a cutaway featureonly partway through the rib 1120 as illustrated in FIG. 43. FIG. 40 isa view similar to that of FIG. 39 but, for clarity of illustration, thespinal cage is not shown.

Also as illustrated in FIGS. 40 and 41B and as described elsewhereherein, it is possible that the rotatable member such as spin-plate 1200may comprise a non-circular feature at or near an end of the shaft 1210,and it may be possible to fit the rotatable member such as spin-plate1200 into the first and second features 1150, 1160 when the noncircularfeature is in a first rotational orientation of the rotatable membersuch as spin-plate 1200 but it may be impossible to fit the rotatablemember such as spin-plate 1200 into the first and second features 1150,1160 when the noncircular feature is in a second rotational orientation.There may be an undeployed configuration and a deployed configuration,wherein in the undeployed configuration no part of the rotatable membersuch as spin-plate 1200 or 200 extends beyond an envelope of the spinalcage 1100 or 100, and in the deployed configuration some part of therotatable member such as spin-plate 1200 or 200 extends beyond theenvelope of the spinal cage 1100 or 100.

The first feature 1150 in the wall may be either a through feature or ablind feature, and the second feature 1160 in the rib 1120 may be eithera through feature or a blind feature.

Referring now to FIGS. 41A, 41B and 41C, there is shown an embodimentsimilar to that of FIGS. 39 and 40, except that the angular rotation ofthe spin-plate from its undeployed position to its deployed position isless than 90 degrees. FIG. 41A shows the assembly of the spinal cage1100 and the spin-plate 1200, with the spin-plate in its undeployedposition. FIG. 41B shows the spin-plate alone in its undeployed position(but for better illustration, the spin-plate 1100 is viewed from avantage point different from that of FIG. 41A). FIG. 41C shows the sameassembly of the spinal cage 1100 and spin-plate 1200, but with thespin-plate in its deployed position.

Referring now to FIG. 43, there is illustrated an embodiment similar tothe embodiment of FIG. 38, except that that the slot may be a groovethat only goes partway through the rib 1120 rather than entirely throughthe rib 1120.

Referring now to FIG. 44, there is illustrated an end of spin-plate 1200near disc 1290. The illustrated shape of recess 1296 is illustrated ashaving a shape of a rounded rectangle, such that a tool for rotating thespin-plate 1200 may reach in through a hole of that is first feature1150 and engage the recess 1296 for the purpose of rotating thepin-plate 1200. The illustrated shape may provide for mechanicalstrength.

Referring now to FIG. 45, there is shown a close-up of an end of thespinal cage assembly. As illustrated, when spin-plate 1200 is installedin spinal cage 1100, blade 1230 may contact rib 1120, while disc 1290may have a slight gap with respect to the nearby interior surface ofspinal cage 1100.

Yet another embodiment of the invention is illustrated in FIG. 46. Inthis embodiment the spinal cage 2100 may comprise a rib 2120 similar tothe rib shown in FIGS. 36-39. The two cavities into which the rib 2120divides the interior space need not be identical to each other orsymmetric with each other. There is shown a through-hole 2252 throughthe rib 2120 and a through-hole 2254 through the wall. It is possiblethat the two through-holes 2252, 2254 can be coaxial with each other.Such a spinal cage can be used with a lateral surgical approach forimplantation, and the through-holes 2252, 2254 can be used for injectingbone-growth-promoting material into the respective cavities in thespinal cage after the spinal cage is implanted. An injection tube can beinserted from the exterior through both through-holes into the moredistal cavity, and then, after completion of filling the more distalcavity, the injection tube can be partially withdrawn and can be used tofill the more proximal cavity, and finally the injection tube can bewithdrawn completely from the implant.

Although a spin-plate 200, 1200 has been described, more generally, anembodiment of the invention could comprise any rotatable or deployableelement that can optionally be used with a spinal cage. Rotation is notthe only possible motion that could be used to deploy a deployablemember that is optionally usable with the spinal cage 100. For example,the design could be such as to use a translational motion for deployinga deployable member.

It is possible to practice embodiments of the invention without groove150, 160. The spin-plate may be designed to exploit amechanical/interference mode of retention without the need to cut intobone. In such an embodiment the spin-plate could be merely asymmetric inits central cross section such that when rotated into position itsvertical height extends more fully into the height of contour of theconcavities of the vertebral endplates and establishes a significantdegree of mechanical interference that enhances the retention againstexpulsive forces that might tend to expel the spinal cage assembly fromits desired position between the vertebrae.

While several inventive embodiments have been described and illustratedherein, those of ordinary skill in the art will readily envision avariety of other means and/or structures for performing the functionand/or obtaining the results and/or one or more of the advantagesdescribed herein, and each of such variations and/or modifications isdeemed to be within the scope of the inventive embodiments describedherein. More generally, those skilled in the art will readily appreciatethat all parameters, dimensions, materials, and configurations describedherein are meant to be exemplary and that the actual parameters,dimensions, materials, and/or configurations will depend upon thespecific application or applications for which the inventive teachingsis/are used. Those skilled in the art will recognize, or be able toascertain using no more than routine experimentation, many equivalentsto the specific inventive embodiments described herein. It is,therefore, to be understood that the foregoing embodiments are presentedby way of example only and that, within the scope of the appended claimsand equivalents thereto, inventive embodiments may be practicedotherwise than as specifically described and claimed. Inventiveembodiments of the present disclosure are directed to each individualfeature, system, article, material, kit, and/or method described herein.In addition, any combination of two or more such features, systems,articles, materials, kits, and/or methods, if such features, systems,articles, materials, kits, and/or methods are not mutually inconsistent,is included within the inventive scope of the present disclosure.

All definitions, as defined and used herein, should be understood tocontrol over dictionary definitions, definitions in documentsincorporated by reference, and/or ordinary meanings of the definedterms.

The indefinite articles “a” and “an,” as used herein in thespecification and in the claims, unless clearly indicated to thecontrary, should be understood to mean “at least one.”

The phrase “and/or,” as used herein in the specification and in theclaims, should be understood to mean “either or both” of the elements soconjoined, i.e., elements that are conjunctively present in some casesand disjunctively present in other cases. Multiple elements listed with“and/or” should be construed in the same fashion, i.e., “one or more” ofthe elements so conjoined. Other elements may optionally be presentother than the elements specifically identified by the “and/or” clause,whether related or unrelated to those elements specifically identified.Thus, as a non-limiting example, a reference to “A and/or B”, when usedin conjunction with open-ended language such as “comprising” can refer,in one embodiment, to A only (optionally including elements other thanB); in another embodiment, to B only (optionally including elementsother than A); in yet another embodiment, to both A and B (optionallyincluding other elements); etc.

As used herein in the specification and in the claims, “or” should beunderstood to have the same meaning as “and/or” as defined above. Forexample, when separating items in a list, “or” or “and/or” shall beinterpreted as being inclusive, i.e., the inclusion of at least one, butalso including more than one, of a number or list of elements, and,optionally, additional unlisted items. Only terms clearly indicated tothe contrary, such as “only one of” or “exactly one of,” or, when usedin the claims, “consisting of,” will refer to the inclusion of exactlyone element of a number or list of elements. In general, the term “or”as used herein shall only be interpreted as indicating exclusivealternatives (i.e. “one or the other but not both”) when preceded byterms of exclusivity, such as “either,” “one of,” “only one of,” or“exactly one of.” “Consisting essentially of,” when used in the claims,shall have its ordinary meaning as used in the field of patent law.

As used herein in the specification and in the claims, the phrase “atleast one,” in reference to a list of one or more elements, should beunderstood to mean at least one element selected from any one or more ofthe elements in the list of elements, but not necessarily including atleast one of each and every element specifically listed within the listof elements and not excluding any combinations of elements in the listof elements. This definition also allows that elements may optionally bepresent other than the elements specifically identified within the listof elements to which the phrase “at least one” refers, whether relatedor unrelated to those elements specifically identified. Thus, as anon-limiting example, “at least one of A and B” (or, equivalently, “atleast one of A or B,” or, equivalently “at least one of A and/or B”) canrefer, in one embodiment, to at least one, optionally including morethan one, A, with no B present (and optionally including elements otherthan B); in another embodiment, to at least one, optionally includingmore than one, B, with no A present (and optionally including elementsother than A); in yet another embodiment, to at least one, optionallyincluding more than one, A, and at least one, optionally including morethan one, B (and optionally including other elements); etc.

We claim:
 1. A spinal cage assembly, comprising: a spinal cage, whereinsaid spinal cage has a wall extending in a longitudinal direction andforming a closed curve in a plane perpendicular to said longitudinaldirection, wherein said spinal cage has a rib connecting said wall withan opposed location on said wall; and a rotatable member, engageablewith said spinal cage and rotatable with respect to said spinal cageabout an axis of rotation, said rotatable member having a shaft having afirst end and a second end opposed to said first end and having a bladeon said shaft, wherein said blade and said shaft rotate about said axisof rotation, wherein said wall has a first feature receiving said firstend of said shaft and said rib has a second feature receiving saidsecond end of said shaft, wherein said rotatable member is rotatablebetween an undeployed configuration and a deployed configuration,wherein in said undeployed configuration no part of said rotatablemember extends beyond an envelope of said spinal cage in a radialdirection that is radial with respect to said axis of rotation of saidrotatable member when assembled to said spinal cage, and in saiddeployed configuration some part of said rotatable member extends beyondsaid envelope of said spinal cage in said radial direction.
 2. Thespinal cage assembly of claim 1, wherein one of said first feature andsaid second feature comprises a cutaway feature comprising a centralcutaway region and a connection cutaway region, said connection cutawayregion connecting said central cutaway region with an external surfaceof said rib or said wall, said connection cutaway region having alongitudinal direction from said central cutaway region to an exteriorof said rib and having a transverse direction orthogonal to saidlongitudinal direction, said central cutaway region having a minimumwidth in said transverse direction and said central cutaway regionhaving a maximum width in said transverse direction, wherein saidminimum width of said connection cutaway region is smaller than saidmaximum width of said central cutaway region.
 3. The spinal cageassembly of claim 1, wherein said first end of said shaft has a firstshaft end geometry and said first feature has a first receiving geometrysuch that said first shaft end geometry fits inside said first receivinggeometry, and wherein said second end of said shaft has a second shaftend geometry and said second feature has a second receiving geometrysuch that said second shaft end geometry fits inside said secondreceiving geometry, and wherein either said first shaft end geometrydoes not geometrically fit inside said second receiving geometry or saidsecond shaft end geometry does not geometrically fit inside said firstreceiving geometry.
 4. The spinal cage assembly of claim 1, wherein saidrotatable member comprises a non-circular feature at an end of saidshaft.
 5. The spinal cage assembly of claim 1, wherein said firstfeature in said wall is one of a through feature and a blind feature. 6.The spinal cage assembly of claim 1, wherein said second feature in saidrib is one of a through feature and a blind feature.
 7. A spinal cagecomprising: a wall having an internal surface and an external surface,both extending vertically and generally parallel to a vertical axis ofsaid spinal cage and progressing circumferentially, wherein saidexternal surface forms a closed circumference; wherein said spinal cagehas a rib connecting said wall with an opposed location on said wall;wherein said rib has a cutaway feature comprising a central cutawayregion and a connection cutaway region, said connection cutaway regionconnecting said central cutaway region with an external surface of saidrib, said connection cutaway region having a longitudinal direction fromsaid central cutaway region to an exterior of said rib and having atransverse direction orthogonal to said longitudinal direction, saidconnection cutaway region having a minimum width in said transversedirection and said central cutaway region having a maximum width in saidtransverse direction, wherein said minimum width of said connectioncutaway region is smaller than said maximum width of said centralcutaway region; and wherein said cutaway feature extends only partwaythrough a thickness of said rib.
 8. A spinal cage assembly comprisingthe spinal cage of claim 7, and further comprising a rotatable memberthat is engageable with said spinal cage and rotatable with respect tosaid spinal cage.